Wishmaster is another horror movie GU entry where the protagonist is a woman rather than a girl or teenager, and the adversary is some kind of demon or killer. It’s amazing how many of these there are!
Alexandra is an appraiser who is given an extraordinary gem to examine, which turns out to hold a djinn (a malevolent spirit), now released accidentally by some kind of spectral analysis. The djinn always tries to get the person who awakens him to make three wishes, upon which the door will open to his world and all the other djinn can come through. He takes the form of a man he has killed and starts hunting Alex, who has visions of the people he torments along the way. All of the people who assist her (companions) are eventually killed. At one point, she journeys to his lair inside the gem, which although not technically underground, certainly gives that impression. She also returns home at one point (due to a wish). Toward the end, she must rescue a family member – her sister, who the djinn has captured. Eventually there is a final confrontation, and Alex makes a very clever third wish and defeats the djinn.