Name That Trauma :: Reader Grokenstein on a Final Girl Finale

Hi!

I've got a movie in the back of my skull that I hope the Traumateers can identify, but it's a bit of a spoiler as it's just the end of the movie; in fact it's just the end credit sequence! There's no music score as the credits roll, but rather, voice-over dialog and assorted scenery shots. As the credits end, the movie abruptly "resumes" for its real ending. Here's the details:

Final Girl has escaped death at the hands of some crazy family/cult/group, some of whom she has killed. Apparently, she was supposed to be "sacrificed" before midnight. As the credits roll and the visuals switch to actor-free scenery, she returns with the local sheriff and deputies, only to find that all traces of her nightmare have been cleaned up. The skeptical sheriff arrests Final Girl after a deputy "finds" marijuana in her car, which she of course denies. As the credits end, Final Girl is put in a jail cell and left alone. She's distraught until she sees the clock on the far wall; it's almost midnight, and she says she's safe now.

At this moment, her "cellmate," an old woman hiding in the shadows in the corner, announces that there's still plenty of time, and lunges at Final Girl as she turns to the camera and screams. Freeze frame as her scream reverberates. Fade out.

…That's it. I have no other details to add, but I need to find out what movie this is so I can see the rest of the damned thing!

Help meeeeeeee!

Thanks,

Grokenstein

UPDATE: NAME THAT TRAUMA SOLVED! Special thanks to Father Merrin for realizing it was WARLOCK MOON!