Your D's obviously under a lot of stress and understandably so Torbaygran. I can understand you being hurt that she doesn't acknowledge the help you're giving; a simple 'thank you' goes a long way doesn't it.
As Feelingmyage has posted "sometimes you have to agree to disagree". Please think carefully before withdrawing the help you're giving them. To do so would only increase the stress she's under and would damage your relationship even further.
A thread for people who have been on GN a long time
What’s a household item that reminds you of your grandma’s house?



Why does the daughter appear to have mental health issues? It sounds to me as though she's worried sick. She's lost her job, her husband is too ill to work and she's got a mother who appears to be a Covid denier (if I understood the OP correctly). Sounds perfectly well to me; just frightened, worried and trying to keep her and her husband safe.