Ok, this is about as vague as it gets, but my husband and his sister both have a memory of being frightened by a movie, and they both only remember one scene;
There's a little girl near a cliff overlooking the ocean, and she's singing. Or humming. Or going "lalala". Both of them remember the tune, but that doesn't help because typing "na na na" a bunch of times isn't helpful, lol.
Also, it needs to be 80s or older.
If you remember any movies with a little girl singing/humming, I'd appreciate knowing the title. I'm sure there are hundreds of films, but I've exhausted my Google abilities.