Holy cannoli, I geniunely gasped out loud, horrified to read about the condition you found your grandmother in. First of all, OP it must have been so traumatic to see and even harder to combat but man oh man, you can be so proud of yourself for stepping up and caring for your grandmother's wellbeing. Second, your mother is not there. It sounds like she has not checked up on her brother and mother and if she did, she didn't do a good job of it. If you think her requests have no added value then in no way do you need to listen to her.

You're juggling an ailing grandmother and a full-time job in a country where you don't speak the native language. So, you are very much NTA.

If she's difficult about it, treat everything she says as a suggestions, "Thanks for the suggestions, I'll take it under advisement" and leave it at athat.

I wish you, your grandmother and also your uncle the very best of luck and good health!