Why does the narrator see a Haitian coffee girl at the end of the story?

The narrator sees a Haitian coffee girl because she is a kind of zombie. Earlier, the professor explained that the Haitian coffee girls 'belonged' to an old woman. They went around in the early hours of morning before the sun came up, selling chicory coffee. When the old woman died, they vanished. They may have been a kind of zombie, controlled with zombie powder, or not. When the narrator sees the girl at the end, it is symbolic of him having turned into a zombie himself. He gave up on life, and so became like the walking dead, alive but with no life or purpose. When he walks into the light with the coffee girl, this could be symbolic of his death, or of his realization that he is acting like a zombie.