Vascular dementia what can I expect?

My mums health seems to be deteriorating but her memory is still quite sharp? Has anyone here lost a parent from this and what can I expect to happen?

Ive read that 9/10 dont make to final stages that the prognosis is usually death by heart attack OR stroke?

All i know is that diet and excercise are crucial to her living longer with this but if she wont do either im scared she may have a stroke soon?

Also have read that vascular can be 4yrs from diagnosis but my mums been ill for at least ten years.