What's wrong with the mother?

Yes. Totally inappropriate relationship with the son, casting aside both husband and daughter in his favor.

It's a great character, very believable. The familial strife all around is brilliantly written. If this were a straight drama with no undead horror it would be touted as one of the greatest films of a dissolving family ever made.

Typical mother behavior for her first born son. She can't see him for the monster he is, only as her baby boy.

She got her wish, a lot like the mother in The Monkey's Paw. Her little boy came home. Sadly he isn't the same boy that left home. But she doesn't want to see it.

What's really weird is her complete disdain for her own sweet daughter. The mother didn't even care if she was alive at the end of the movie.

No blah, blah, blah!

I thought she wanted so desperately to cling to the past and wasn't willing to move on. Things weren't the same anymore and she wouldn't accept that. She tried to keep the past alive and was in denial that it would never be the same again.