According to the biography, Wihelmine died of edema/dropsy as a follow up on her earlier tuberculosis. ("Dropsy" aka Wassersucht seems to have been something a great many Hohenzollern - FW most famously, but also several of her sisters - were prone to have; Wilhelmine didn't show any symptoms until the last year of her life, but then it came with a vengeance. The tuberculosis, otoh, had been ongoing far longer and was a reason for the France & Italy trip, yes.