You are in a difficult situation.
I have two daughters now 32 and 27yo. the older one came to live with me at 12y12yyoo. Dad's girl we are very close. The younger one pulled away from me at 14yo and up till 25yo came in and out of My life in a destructive manner. In the end I decided for my own mental well being, to terminate the relationship. Needless to say she is as toxic as I found her mother to be.
And that's ok now with me. Both sister despise each other.
So, back to your situation. Do you have any ideas on why both daughter's have drifted. One would think they'd love a grandma doting on their kids?
The daughter that sees a psychiatrist might have deep issues. I hope you get the opportunity to say "if I can contribute to your well being let me know"
My eldest had a step mother for 10 years. I didn't realise for years how my partner was mentally abusing her. I said those words to my daughter when she began visiting a psychiatrist and the flood of tears came. She told me I didn't protect her enough. We talked it out and I apologized. It hurt me but thats what a good parent has to do.
I hope this site helps.