My personal head cannon is that Carmilla kept her childhood home and would occasionally hide away there when ever she wants to be left alone. All the locals obviously think it’s haunted and won’t go anywhere near it. Anyways, after saving the world, she takes Laura there. Laura wakes up early and takes that opportunity to explore the place (even though Carmilla told her not to wander off by herself because the place is old and some parts aren’t entirely structurally sound).
If I had and capacity for writing I’d give you an accompanying fic, but I don’t so instead you get an illustration.