As it turns, the woman who owns the house is no other than Mom who is waiting patiently for Harry to get his backpack from.

“Well there, young man,” she is addressing to Harry in particular, “It looks like you need to get going in your adventure real soon. I have your backpack packed up for this occasion. I do apologize for not foreseeing people arriving in here and feeling cramped right now.”

She brings up the backpack in question up to his face so he can see better.