Not counting the postscript (which is the author's commentary on the novel) the ending is from Dedé's perspective. She says that to chase away the evil memories at night she must remember all of her lost loved ones and usually comes up short:
"And I count them all twice before I realize—it's me, Dedé, it's me, the one who survived to tell the story." (4.13.196)
Dedé is so used to being in her sisters' shadow—and telling their story—that she forgets to count herself. The novel is an attempt to remedy that, to give her a voice alongside her sisters'.