There's probably no harm in at least asking about it. [Teaching something that could be used for self-defense could easily be considered useful, but yes, there is the question of how much interest or demand there would be.] That way you'd know if it's an option or not.

I don't have much left back home, myself. I was actually on my way out to look for a new place when everything happened and we all wound up here. [Not a lie, yet not the whole truth either. Either way, finding herself here might just prove to be a strangely convenient coincidence and give her the start she's looking for.]