Someone or a group of people should show up at every race early and run with her. Just let her know you are doing the early start and get there really early at like 5 so that she cant beat you there. Then just wait for her to arrive aandrun with her or behind her with a go pro on your head or body or something.
Here is exactly how it would work
1. A group of people pitch in enough money for a go pro.
2. One person from hopefully a large group of people would take their turn and run with her and film it every time she runs.
3. If she is legit, than thats great, but if she isnt, I would say after about a month MAX she would be done.
4. If 14 people or so were in the group than each person would only have to run 2 marathons per month, which wouldnt even be that bad.
5. There would be irrefutable video evidence, that even an nfl ref couldnt overturn.
6. Her and the other guy would be forced to give up their record
7. They would both be sued out the wazoo for false advertising.