I'm on the other side of the "this is crazy here".

It's a family member crashing at her place for a few hours while she's away. Is it possible that he's a creep? I guess, but then get him on a webchat and suss him out. If there's a reason he gives off a creepy vibe, then yeah don't let him in your house. And ok, why not lock up a few important things somewhere and tell him not to poke around in certain places? sure.

But otherwise, come on, I've had friends of friends crash at my place. Not that big a deal.