My grandma

I’m having a really hard time right now. My grandma almost 90 years old. She was just diagnosed with cancer. She’s refusing treatment, she doesn’t want to fight. She says she has a lot of people waiting on her, and she does. All her family, my grandpa, her friends, everyone has all passed on. Her doctor told her 6 months to a year is what she has. It’s tragic for us because she doesn’t want to fight, she has fought a lot during life she has beat cancer before, lost a couple children, she has been thru it all. I understand why she doesn’t want to fight, I get it. Now the other part I’m worried about has to do with my dad. His world has shattered. He’s not going to be the same and I’m pretty sure he’s done with me, my mom, and my brothers. He doesn’t want anything to do with us and shut down. I’m pretty sure my family is lost now. Shoot, I might not even have one far as a mom and dad. I’m pretty sure I lost my dad. I didn’t do anything wrong but the way he is and the conversation I had with my mom, he don’t want no relationships with family after she’s gone or even right now. Anytime I message him he’s always mean. I grew up with him he’s a narcissist. I’m at a point to where idk what to do. Should I go to the funeral when she passes? Will their be one? He don’t want anyone knowing her business. There’s nothing I can do. This one person who passes my son won’t ever know his grandpa bc he’s this closed minded. This is part of grief. She’s still alive but he knows she will be gone sooner than later. He’s a mommy’s boy and honestly I’m just numb idk how to feel.