So is this baby in a foster home?
Sometimes people do things because they themselves felt abandoned and unwanted. Considering how the child turned out disabled because the mother did not stop doing drugs, I think it was best the mother gave her up rather than her living her life being neglected.
I would not hang a picture of the child's mother above her crib like that and lie to the child telling her her mother loved her. I would just provide love and affection to the child. A child in a crib is too young to understand why this woman in the picture who is supposed to love her isn't there for her.