Who comes to stay with the narrator in Chapter 19 and why?

The narrator is dismayed when the ex-milliner asks if he and his wife can stay with her for a few days while their house is being repainted. She knows that the couple's presence is dangerous to R by its very nature, but she also knows that to deny their request would attract too much attention. So she is forced to offer them a place in her home, though she knows that it means that R will be completely cut off from other people for the entirety of their stay, since the narrator could never chance being caught entering or exiting the trap door that leads to R's hidden room.