P.W.
Gramma,
I'm so sorry. It must be so difficult to watch your friend in so much pain. Surely you want to fix it, but of course it is out of your control. Just do your best to be a support for your friend. Non-judgemental and an open ear. If she will not seek help that is her choice. It is her journey.
I am no expert, but Perhaps your friend could write a letter to her daughter. I would caution her not impose any guilt, etc... I would think if she could just reinforce her love and to let her daughter know she will respect her wishes, but if at any time her daughter changed her mind she would be waiting in the wings ready to communicate or help in any way that would be comfortable for her daughter. Then find some place to volunteer that might help uplift herself, but respect her daughters wishes.
You, again, can offer support. Help your friend let go of the past and what could of been. Let go of any guilt. Mostly just listen and love her.