Her Parents.........
We find out at the end that she knew about the box from the very beginning.
So what was her plain? - To kill all that knew and meet her parents at the stop?
Also, we figured out the Asians guys and The guy dressed like an old lady were some type of agents who's only purpose for being on the train was to get the box. -
But what was the young female's connection to the box - how'd she know about it? - Was the biology book and parents just a front?
"And what was it last time? Didn't know what the box was?" - The Female Cenobite in Hellbound