What do the two strangers do when they visit the family's house?

The two strangers are a couple of thugs working for the government. The narrator's family lives in the Dominican Republic, which at that time was controlled by a brutal dictator called Trujillo. The strangers are functionaries of the dictatorship, probably members of the secret police. Earlier in the story, the narrator had an unpleasant encounter with the two men when she was out walking her dog, Liberty. The men are described as "strange" and are wearing dark glasses. It would seem that they're spying on the narrator's family as they're known for being hostile to the regime.
Later on, as the family wait outside the house, ready to leave the Dominican Republic for their new life in America, the narrator imagines what will happen after they've gone. She envisages the two strange men from earlier in the story entering the house and completely trashing the place: destroying old photographs, knocking over the coffee-table, throwing cushions on the floor, and smashing windows.