Objective: Scare the three witches away.
Firetail may be freed by binding Raindancer to the water fetter in the basement's magic circle and casting Rain; however, this will break the circle that the witches have set up, making your ghosts vulnerable to banishing. Consider bringing along an air elemental and an earth elemental, then bind them and Raindancer to their respective fetters. This will complete the circle and give your ghosts immunity, allowing you to scare the witches without worrying about them getting banished.
Hogwash can be freed if you have any of the mortals wearing electronics pass through the back entrance to the sorority house. You can also have Tricia make an Ethereal Gift while still bound and try to get any mortal to carry it through the back entrance.
To free Tricia, you will need to manipulate Blair Whelchel to the upstairs bathroom. This can be attempted by occupying the lower floor bathroom, and otherwise causing a small amount of fear to have her move from the lower floor.
The objective is to scare off the three witches, recognized by their darker clothing. It is easier to build up power by using a strong fear effect (such as Dread) in the lobby. When you have enough power, order some of your ghosts to pick on the witches and have them roam.