I see the problem here, there’s a baby in your body!

Coherence, Funny Games, Green Room, Misery, The Thing, and The Lighthouse are all good single location horror/thrillers that come to mind.

mother! is a cerebral and artistic horror film that all takes place in a singular house. This one isn’t for everyone though, as it’s very metaphorical and disturbing.

Less horror and more thriller but Locke is a phenomenal one-location film as well