I don't think it's about age as much as what neighbours have been saying about her moving slowly recently. I believe she had a slip in the shower or something? It happens.
She was mentally robust, but physically, no not necessarily, she was a small woman, she always had an odd gait in the last few years, suggesting back or hip problems, she was nearly 80, and however sharp you are mentally, it can happen to any of us at any time. Particularly when we're that age. She wasn't Wonder Woman and I'm not sure why people are talking as if she was.