At the end of Chapter 17, why does Odile stay at the hospital after 9 p.m.?

Odile is about to leave the hospital around 9 p.m., but a private named Thomas reaches out and asks her not to leave. Odile tucks a blanket under his chin and talks to him about the library. After a while, she notices it is 11 p.m., but he asks her not to leave. She tells him he will never be alone. She tells him more about the library and the subscribers. She stays through the night telling him tales, calming him, and holding his hand until he dies.