At the end of Cai Jun's novel Cat's Eye, what happened when the girl saw the candlelight in the opposite building? Seek an explanation

Xiao Ye said: Cat's eyes made of radioactive elements in a dark room can make people hallucinate and interfere with brain waves. But the black house has been burned down and the cat's eye on the door has been tested.

This is a suspense, you can interpret it any way you want. Maybe it's an illusion. The dust settled. Perhaps it is the rebirth of a nightmare, which is of great significance, or perhaps it really knows more than we do.