In love with a Demon

A teenage high school named Liza who was being sended to Oregon to live with her grandfather, Stanley and Stanford Pines, and their neice and nephew, Mabel and Dipper Pines.
She loved it there until one day something happened that made Liza's life change.
Dipper and Mabel warn Liza about a demon named Bill Cipher, and she has to be careful around her surroundings for him.
Keep in mind that this is when Bill was defeated by Stanley Pines who tricked him to save his brother Stanford, and it was when Mabel, Dipper came back for more adventures with their uncles.
But due to Dipper's warning about Bill Cipher, Bill ended up lying to Liza in her dreams. He wanted Liza to find his body that was turned to stone and summon him.

Can Liza defeat the demon or will she fall with the demon?