What Ever Happened to Aunt Alice? (1969)

As Aunt Alice, Ruth Gordon applies for the job of housekeeper in the Tucson, Arizona home of widow Claire Marrable in order to find out what happened to a missing widowed friend, Edna Tilsney. The crazed Page, left only a stamp album by her husband, takes money from her housekeepers, kills them, and buries the bodies in her garden. Alice is a widow too. So is neighbor Harriet Vaughn. Lots of widows here.