She's somewhat relieved that he puts any stock in her theory. What is she even suggesting? Underground tunnels? She's not 100% sure herself, but she has a distinct idea that whoever these people were, they didn't just sit in their houses through all the crazy weather. It would make anyone go bonkers.

"You...woke up in a cave? Do you know where it is? We could check there. Or...I don't know, maybe there's a crawlspace under the house or something like that. I guess I hadn't thought to look."