We don't ignore discussions of domestic violence here. I grew up in a violent household, and I know how many people do ignore it because it's easier. I absolutely would talk to my children about it.
I'd also be very inclined to ask the mother if everything was okay. I doubt she'll admit to anything, but being in a violent house can feel so alone. Knowing that someone is aware is oddly helpful.
Of course if it wasn't something abusive, then she probably would rather know to talk to her child about it to clear things up. I'd hate to know someone assumed I was being abused because my child told a story that wasn't true.
I'd also be very inclined to ask the mother if everything was okay. I doubt she'll admit to anything, but being in a violent house can feel so alone. Knowing that someone is aware is oddly helpful.
Of course if it wasn't something abusive, then she probably would rather know to talk to her child about it to clear things up. I'd hate to know someone assumed I was being abused because my child told a story that wasn't true.








She might really need a friend, and it may also be a situation that could be hard to be a witness to. (Or she could have a child who was mistaken with that one comment, but that wouldn't be my first assumption given the circumstances.)

: OMG, good point, I had it in my head that the OP did know the woman well enough to know she wasn't that sort of scary.