Hi J....
I read through the responses from the other mom's and for the most part, I agree that it's probably a security issue, at least in part. Your daughter may have just been missing you or home. Or, she may have just wanted the doll and not wanted to put it away yet - so it could also be a control issue.
I am a single (divorced for 3.5yrs) mom to my six year old son who has run the gamut of emotional meltdowns - so I can empathize with what you're experiencing.
My son has a red fleece blanket that he has had since birth. He calls it his kiki. It goes everywhere with him - though when he was four we started with some rules about where it could and couldnt go. It could go to daycare, but he could onbly have it at nap. He could bring it with him when we went grocery shopping or to a restaurant, but it had to stay in the car. Not letting him have it non-stop seemed to help him be separated from it when he needed to be throughout the day. It helps it kids have clear expectations. When we would leave to go to the store, for example, I'd tell him "We're going to the store now, and you can bring kiki with you, but it has to stay in the car while we are inside the store. You can have it back after we're finished shopping."
I totally understand taking the doll away because of her behavior (I have done the same thing), but I think in this case, the punishment might be a little harsh. Without knowing your daughter or your personal circumstances, I think that the issue with the doll is merely a mask for something else that is going on. Has there been any recent change in your daughters life? My son has started acting out in school (Kindergarten), getting mouthy at home (backtalking), and having accidents - when he has been completely pottytrained since he was three. We moved on December 22nd to a bigger place and around the same time my sister moved from Fox Lake Illinois to North Carolina, and didn't get a real chance to say goodbye to my son. They are very close and she was our only family in this state. I'm sure most of my son's bevahioral problems relate to all of the change. The move was a positive change (we were living in a cramped one bedroom apartment and now have a spacious 2 bedroom condo), but it was still a change. He has to get up 15-20 minutes earlier in the morning to go to his babysitter's house (I kept him at the same school though it makes my commute tough). My sister moving was another adjustment for my son to make. I couldn't figure out why my son was having accidents, so we've been talking about them for a few weeks and finally he told me he has been trying to hold his bowel movements in, so that he doesn't have to go to the bathroom as often. This, too, is something he is trying to control. With all of the changes - large and small - he feels like he has lost control and is doing whatever he can to feel like he has control over SOMETHING, anything.
He has been misbehaving in school and I was mortified to hear some of the things that has been going on - he ineterupts the teacher, mimics (mocks) her when she's talking, refuses to stay in his seat, leaves circle time, blurts out answers when it isn't his turn, etc. He complains of stomach aches and other mystery illnesses and says he's too sick to go to school. Finally after about two weeks of talking, I found out that one of the kids in his class has been making fun of him, teasing him about his name (his name is Ian, the other child is calling him Peein' Ian), and takes things from him when they are playing in the centers in class. I told his teacher about it and she is going to talk with both kids on Monday.
Maybe there is something else going on in your daughters life. Does she see her father - has the schedule recently changed (past month or two)? Has her routines at home changed at all? Is there somebody new in her life (new friend of yours)? Is it a new daycare or one she's been going to for awhile? is there a new teacher in her daycare class? Kids don't feel like they have any control when there are hanges in their lives.
At four years old, your daughter is old enough to understand that her behavior is unacceptable. If you haven't already, you should talk about how biting hurts and that it is not allowed. tell her up front what will happen if she bites again - and talk about it at last every couple of days so she doesn't forget. With my son, if he hits someone, I know he will get punished at school or the babysitter's by sitting in time out - but he knows that when he gets home, he is going to lose a priviledge there, too. (usually he loses watching a movie or tv in the evening). If he has a meltdown, he goes to be dearlier, because perhaps ne didn't get enough sleep. If he hits someone with something, like a toy, he loses the toy. I took things away for 24 hours when he was 4, 48 hours when he was five, and now, a 6, he loses thimgs for three days. I make sure he knows what the consequences will be for various misbehaviors, so that he isn't surprised when faced with the punishments.
You might want to make sure she understands the rules about the doll, for example. "At circletime, you need to put your doll in your cubbie, but you can have her back at lunchtime". Explaining things like that will help ensure that your daughter does what she is expected to, but also reassures her that she will her her doll back at a pre-determined time (nap) - it will give her a sense of security to know she can have it back at nap.
I started a behavior modification chart with Ian when he was four and it worked wonders - I never should have stopped. We recently started it up again and his behavior is steadily getting better. It might be something you are interested in - you reward your daughter for positive behavior (maybe a stocker everyday that she doesnt throw a tantrum, or whatever you want). These charts can be used age 4 and up and there are many methods.
some info: http://www.latitudes.org/behavioral_charts.html
http://www.familymatters.tv/level_4/parenting/childbehavi...
Good luck. I don't know what kind of support network you have... but if you ever need to vent to another single mom, feel free to email me at ____@____.com.