Does a Quit Claim Deed Supersede a Will?

My grandmother is age 97 and lives with her son and his wife. The son works f/t and pays a care-giver to watch my grandmother. About 3 years ago now, the son had a deed drawn up and had my grandmother sign it (not knowing really what she was signing). The son put in there that he paid $1. to my grandmother for her old, small vintage home and 20 acres. He said since he has cared for her and she dearly loves him. That's what the he had written up in the deed.

So long story short there is a will and there is another sibling involved here and a deceased sibling with 3 children. The home and 20 acres are suppose to be divided between them all not just the son! He put his name and his wife's name on the deed. The wife's name, really! She should not even be on there. I feel like this is financial elderly abuse and taking from an elderly woman when she does not even know what she signed nor can she really see at this time. What are your thoughts? I feel her son is trying to take all and over-ride the will.