Her father is located in one of the piano rooms inside Haunted House. There are four hallways in the house, accessible through the far left and far right doors from the entrance hall when you enter the mansion. Each hallway has a rendition of a certain room, e.g. the piano room in your case. This means there are four possible Piano Rooms in total, one in each hallway.
Olivia's father is located in one of these four. Find him and talk to him to complete the quest and start the next one in the chain.
Hint: Its in one of the hallways that are not upside down.
PS. If you're not familiar with the mansion layout (its easy once you get used to it), bring plenty of Return Scrolls for if/when you get lost.
The term "wall of text" only applies to ignorants who do not bother to read their opponent's mostly perfectly valid arguments before immaturily attempting to counter them.
