Thank goodness it isn't his mailbox. She didn't want her to get in trouble in vampire territory. The information she'll find there will no doubt give them a little clue about the man they're looking for. Better than nothing, right?

Definitely after this. It's a good thing we're intangible, Clara can't help but think as she 'hops' back when he moves closer. No worry of awkward contact oh no.

"Um-- We're simply looking for an acquaintance of ours. There's urgent news that concerns him that we need to tell him." What she's doing isn't lying to a man. Oh no. It's telling the truth in a rather obscure and vague way. That's the truth, friend. It's the only possible way to keep a straight face without looking guilty. "It seems he isn't here anymore though! Looks like he forgot to send us his address when he moved."

How he knows two lady ghosts and how he's expected to inform them of his move is a little bit of a stretch but anything is possible when someone is (un)dead.