i would take a piece of paper and write the woman's number plate/car model/what happened. and stick it on the damaged car's windshield.
a similar thing happened yesterday, a young girl was pushing one of those supermarket trolley heading to her car, she took her stuff out and pushed it away, it ended up hitting a BENTLY! i was horrified.
i didn't do anything though, the girl left instantly, and the guy came later, him and his friends had the bad boy scene going one, i wasn't arsed when i saw them.