Conversation so far:
who kills tree gelbman in happy death day
Tree is lured into a tunnel and murdered by a figure wearing a mask of the school mascot.
How did Lori plan Tree Gelbman's murder in Happy Death Day
Lori gives Tree Gelbman a poisoned cupcake.

Question: Why did Lori plan the murder
Self-contained rewrite: Why did Lori plan Tree Gelbman's murder in Happy Death Day