Deimus how to convince the ghost to leave the house, i'm so confused
After you have defeated the boss in the forest, talk to Bert in the guild, and he will inform you that Evie is at the abandoned house. After talking to her, you'll need to figure out a way to stay up late and visit the abandoned house after midnight.
Energy potions will allow you to stay up late and meet the ghost at the abandoned house after midnight.
Talk to Evie the next day, and she will inform you that you'll need a spirit stone to fight the ghost. The spirit stone is sold at the pawn shop next to the guild at night.
Equip it, use an energy potion, and visit the abandoned house after midnight to meet the ghost. Let her defeat you twice to progress the story.