The woman is just deranged. You have nothing to fear, the Humane Society would scoff at her for absolutely wasting their time. They have plenty of food and water, and I don't see any horse in alarming condition. I'd prefer to see a bit more meat on them, since they're lean enough that it would only take a few days of going off feed to see more alarming condition, which is why I like a good healthy weight, it's easier to notice if something changes and do something about it before it's a problem.
All in all though it's your choice, and none of them look starving.