Thats really sad that happened. We had a neighbor that would do stuff like this not because she thought she was being helpful but because she thought that it was ugly and wanted it cleaned up. Sounds to me that your parents neighbor is the same.
You should have your parents tell her that they would be happy to trade something in exchange for the peaches they gave away.
For us it was a neighbor who kept offering up my services as a mechanic to fix peoples cars. She figured since I did it for neighbors and friends for free when they needed help, that she should spread the love to everyone. Problem with that was, she was offering someone elses time, and that I took it case by case depending on how "in-need" the person asking was, and whether I had the time. If it was someone just looking for a handout I would refer them to a good mechanic, but someone in a jam depending on the car for a job or something ...
She took it as a opportunity to offer this to any and everyone people I had never met, and so forth. It was easy enough to fix, I just told her, to feel free to give out my info and I would be glad to do work on the people she sent my way, if she would just take over the music lessons (she taught music out of her home) for my kids in return, so I could offload that burden and free up some time to work on them. Suddenly she didn't like to offer her time up free and quickly back pedaled out of the situation. I have not had that issue since.