Negativity and depression. Any suggestions?

I’d contact her doctor and let him/her know what you’re seeing. The doctor can’t discuss it with you but you can tell, either by letter or in person, and make an appointment for your mom. Tell her whatever reason she needs to go, an annual physical, an insurance requirement, anything but to discuss her emotional issues. She likely needs medicine to help things. There’s no cure for dementia, it will only worsen, but stroke can bring on depression and there are meds to help with that. As for your time and money, no one, whether or not it’s your mother, has the right to demand either. Your mother shouldn’t know anything about your money, and your time is yours to share as you choose

Your profile says Mom suffers from a stroke and Dementia. Stroke itself has probably done some damage. People suffering from Dementia can no longer reason or show empathy They get self centered. Nothing you do will make them happy. They have lost that ability to appreciate.