I don't think the anavar would have pushed her into menopause prematurely...not in the sense of full blown. True, it could easily, especially at her age bring on similar symptoms after she stopped using it, but that would regulate itself after a short while off IMO. But then you have to consider she's already been off for 6wks, this should have been enough time for everything to "clear up." For that reason, she may very well simply be at the stage where menopause is just where she's at in life.
My advice, give it another wk or 2 and see how she feels. If the hot flashes persist, maybe it's time to go to the doc and get things checked out.