Following the death of Madeline in "The Fall of the House of Usher," with what does the narrator assist usher?

The narrator helps Roderick Usher move her body to another part of the house and secure it in a "vault" of sorts.  The narrator and Usher believe that Madeline has died when they do this, but the reader finds out later that she, in fact, is NOT dead.  When she appears at the end of the story, she falls upon her brother and he also dies.  The narrator manages to escape from the house before it crumbles.