Tragic case. I've got three healthy, happy, intelligent, athletic children (yes, I'm lucky and blessed) but I would not force my child to live without a brain. It sounds like the mom is just selfish and won't let go. Her daughter isn't even in there.
I can't help but wonder how healthy the mother was before and during pregnancy. Growing a little life is serious business and some mothers just don't understand that.
Last year a girl my daughter knows got pregnant. She's unemployed, obese, not too bright, not in very good health and smokes. I figured she would quit, but she and her boyfriend continued to smoke throughout the pregnancy. She had her baby and I can tell the poor little guy has issues. He's not alert or observant like a developing baby should be. It gives me the sads when I see the little guy.
My wife was told at 16 she would probably never be able to have children. We met young and she did everything she could to live healthy in hopes we could conceive. She ate healthy, exercised, played sports, no drugs or smoking, only light drinking, etc.
Eventually she got pregnant, and then she educated herself and did everything she could to grow the best little life inside of her possible. I credit her for the wonderful kids we have, because it wasn't my genes that did it.
I see way too many babies being born with health issues because of irresponsible mothers. Growing little lives really is serious business. At least that little girl in the OP doesn't know she is suffering, I hope.