"I was torn between just sending back by mail or leaving it with the train/metro station manager. In the end my thoughts were she was on vacation since the address said California. She would need her purse to get back home. I really wasn't sure what was best. I was torn. "
If you left the station with it, you could have been charged with theft. Even if your intentions were honorable. You did the right thing, hope the train station people are as honest as you.
OTOH, WTH was she doing carrying that many credit cards!! That is CRAZY! I have a lot of credit cards but only one or two are in my wallet at any time, the rest are at home. Just because your wallet has all those slots, doesn't mean you have to fill them up with credit cards!!