Some advice needed.

Hi there, I am new to this site happy to have found it :) So my grandmother always lived close to us, my dad used to see her every evening have dinner there and so on since he was her son. Me and my mother were there every now and then. My grandmother has always been able to live on her own. 3 years ago my dad passed away suddenly of a heart attack. That left my grandmother with the loss of her oldest son. She is now older and cannot get out of the house, she has diabetes and all other kinds of issues with her health, both mentally and physically. She does not want to really accept my dads death and I understand that but it can get hard at times. She does not want to move, and is really stubborn about things. My mom is with her everyday and so am I. We both live on our own and have small living spaces so none of us can really take her in. And like I said she is stubborn. She has 2 other sons that unfortunately live abroad and cannot do much from there, and she refuses to go be with them either. When they call she says everything is fine. I feel very overwhelmed since things get worse, she has hallucinations and has been very unstable at times but when the doctor asks she is again fine! And I feel really powerless to the situation. I know it will not get better or easier and feel like we have no support at all. I am not even 30 years old yet and feel clueless. Any advice? So sorry for the long rant, needed to vent I guess.