I am a nurse, not a doctor. I won't speculate on her condition but to say she sounds very very sick.
I think what needs addressed is the fact that her mum CAN'T stop. The alcoholism is a disease in itself and your daughter needs to understand that even though her mum knows that it is killing her, slowly and painfully ...it will always come before her, her mums health, and anything or anyone else.
whether her mum stopped tomorrow is irrlevent because she won't. She can't.
It's okay to have hope. But to tell her yes, sets her up for thinking when her mum does pass away (and she will)... that had she only asked her to stop, begged, pleaded and cried for her to stop....that she would have and would still be alive.
She would be shouldering guilt that is not hers to carry.
Seeing how serious the situation is now I would suggest a therapist for your daughter that specialized in alcoholism in families. it is better to have her aquainted now with the idea of sharing her feelings and trusting someone outside the family rather than when her mum does pass...
good luck. Praying for your daughter.