I was NMS (1982) and I couldn’t tell you for the life of me what I got on the PSAT! Like everyone else upthread, you didn’t prep for it. And you only took your SATs once – unless you were a poor student, then you took them twice.
You only see this woman at family functions. Do you really think that “oh, yeah, you only got an XX and my kids got YY, so they indeed ARE smarter” is going to be a productive conversation? Do you think you will convince her of anything? Just have your kids tell her that gosh, she really is indeed smarter (they can cross their fingers behind their backs) and move on. I agree with the posters above – it’s more pathetic to try to rebut her.