Board Thread:Questions and Answers/@comment-24084046-20151011075435/@comment-26871105-20160510154938

Joseph talked with Lisa Lisa after finding out about Dio's re-surfacing, which would mean Lisa Lisa was about in her mid to late 90s during that time.

And given that Joseph traveled to Japan shortly afterwards without ever showing concerns throughout the entire Part 3 on the currently wellbeing of her, I say it can be assumed that she'd already past away before the start of Part 3.