I went back to read your other posting so that I would know what you're talking about.
First, next time, don't agree to 2 weeks. 1 week is the longest guests ever need to stay unless they are coming from another country. I have a great relationship with my parents, and 2 weeks would wear me out. Just say no! But since it's too late for that now...
Whether you put your foot down about your MIL coming or not should depend on how much damage she actually does. If she's unpleasant and you hate having her there, but she comes rarely and it's important to your husband, then you let her come. Teaching your daughter how to deal with bullies is an important lesson, even if she is a little young to be learning it. Give your daughter a couple of good responses to say to Granny, such as "That's not a nice thing to say," or even, "If you can't say anything nice, don't say anything at all." I'm sure you can come up with your own, too, and do as much as you can to keep your daughter from ever being alone in a room with Granny, even if that means she is in the kitchen with you while you cook.
But if Granny says things to your daughter that change your daughter's opinion of herself, or you can see that the things she is doing is causing lasting damage, that's a different story. Your first responsibility is to protect your daughter, whether or not it puts your marriage at risk. I have had two friends who had to stop and say, "No, that person can't come in my house." One had the support of her husband, and the other is now divorced. But both did what they needed to do to protect their children. If your husband doesn't support excluding her from your home, encourage him to to see her alone, or even, if you have to, get a hotel room for you and your daughter and visit with Granny only when you can be there to supervise. But I very much hope it doesn't come to that.
Good luck.