My husband great aunt lived into her late 90's. She was healthy and independent for nearly the whole time. She just started to get very tired at the end. I think she moved in with his grandmother just the week before she died peacefully in her sleep.

His grandmother was quite old too when she passed away, she did have some dementia when she died, but mercifully her decline was pretty steep, so it was not long after she showed the symptoms and became dependent on others before she passed.

My dad's mom I think was in her 80's. My mom's mom is still alive.