If you remember the one where the kid was haunted by the girl his mother used to bully—- strong negative feelings can manifest curses.
The kids mom had some nasty feelings towards the kid, so when Kaya exorcised the kid— the mom died. That’s why the chapter ends with Namu saying it doesn’t matter if the pictures were exorcised since the mom involved never loved her kid and wouldn’t order pictures of her kid.
the mom hates the kid so much the hatred became a curse that’s directly tied to moms life.
Curse dispelled- mom died.

That kid ,mother wasn't dead so how did she possessed her daughter