The thing is, that's her BABY. that's her child. She watched Dess grow up from perhaps looking exactly like her, or maybe exactly like her father, to let her develop to become her own person with her own distinct style (that maybe she didn't completely understand, but the way Dess looked so happy while wearing those silly dark clothes and singing those obscene songs made up for it all a million times over), to not see her at all.
Then, an opportunity. And it's not exactly her, her body is warped and monstrous and long and scary, but she knows it's her. How could she not? And how could she not try to keep her alive that way, even if it means she may not look like that punk teenager or her mother or her father anymore?
She thinks that maybe, once this whole plan is over, she can hand her baby her guitar (that she probably got her herself, at a birthday party or on Christmas) and hear her play just once more. Maybe she can tell Rudy before he gets worse. She can show Noelle that all the pain, all the suffering was for something. Kris should be grateful, too. She can bring her baby back.