Rosa and the Executioner of the Fiend (2009)

Rosa, a Holocaust survivor, is an octogenarian widow who has lived alone for more than 50 years in an apartment across the United Nations. When an intruder gets hold of her place, she takes him for a thief, a rapist and then a Nazi agent. But he is none of that. His mission is "to execute the greatest S.O.B. the world has ever known".