I found the diary in the cemetery that details how to perform the exorcism, (with a subtle reference to the movie "The Exorcist"). It says I need mandrake root, rosary beads, holy water, and holy scriptures. I got all of those things in my inventory and went to Francesca Gulvardi to exorcise her, but it doesn't give me the option to do so. Is there a way to do it? Thank you for your time.

Ah, nevermind. It turns out I had to go to the herbalist and have her turn the mandrake root into a potion first. Now if I could only find that stupid hammer and Thintan....

Check the maps of the Devil's Caverns (outside) and Wasteland in this thread.

Ah, that's where the hammer was. Thank you. Unfortunately Thintan, whom I met in the Wasteland earlier, was not in West Glatzburg where he should have been, so I had to use the type \addbeing_afriend Tinthan -1 -1 code. I'm not sure why he doesn't appear for some games. Thank you for the help Kovi.