D..
JP, I'm more worried about him during the day, to be honest. I have no doubt that you are right in your assessment, but truthfully, his behavior during the day is more worrisome. Without handling the daytime, the nighttime cannot be fixed.
He needs loving but firm and swift consequences for what's going on during the day. He needs to be able to "use his words" with you and learn to use talking instead of acting out. You haven't mentioned his speech abilities, but you must encourage those. Help me (pronounced 'ep me since the "L" is hard for a 2 year old to say) is important to teach him. When he can say this, he knows you understand him when he needs you. "Wa-wa" for water, etc. When he hits you, grab his hands and don't let go (even if he doesn't like it) and firmly say to him while controlling him by holding those hands, "Hands are for helping, not hurting. You may not hit mommy." Don't let him get away with it. If he kicks, put him in his room and let him cry. When he finishes crying, open the door and ask him if he is ready to behave. Hug him and tell him to tell you he is sorry. Remind him that he is not allowed to kick. Same thing if he has a tantrum. NEVER give him what he wants when he has one.
If you are tough now about these tantrums and daytime behaviors, things will get better. At nighttime, just keep taking him back to his room. Put his crib mattress in the floor so he can't hurt himself.
One thing that Supernanny does with kids who continually try to come out of their room is have mom sit in the middle of the dark room, not moving, not talking, not facing the child. If the child gets up, she puts them back in the bed and sits back down in the middle of the room again. Eventually the kids get bored and tired of it, and go to sleep. It takes a long time at first, and then gets better.
The thing is, if you allow him into your bed anymore, he will scream and tantrum to get back into it. Neither of you need this. Instead, don't allow it anymore, period. Yes, he's going through separation anxiety. No, it's not going to ruin him.
So try the supernanny approach, and really start being totally, 100% consistent in everything you do with him. He is begging for it right now, and he needs it too.
I hope your mom gets better real soon - I'm so sorry about that.
Dawn