The Song That Doesn't End on loop for the entire duration of the movie. At various volume. I'd write it in as a spirirt trying to fuck with people. The volume is proportional to the characters' distance from the vengeful spirit, which moves freely about the old abandoned mansion.
Anything by The Caretaker. Especially Selected Memories from the Haunted Ballroom, which is inspired by The Shining. It would be cool if it came full circle to being used in a film.
Alternatively, Disintegrating by Myuu
"Once Upon a Dream" from sleeping beauty. The protagonist is at a ball for some reason and the killer/monster is on the other side of the room, and then every time they look away it's dancing with someonecloser to them, and they're trying to flee but they have to push through the crowd.
