Technically, since the company paid for the ticket, they'll probably want the credit for themselves. However, since many times they are not transferrable, she might be left paying the company for her ticket.

I had this happen to me once - I left a company after they had booked a lot of us to travel to LHR for the annual corporate gathering. The ticket was on VS economy and when I left, since I was no longer attending the event, the ticket stayed in my name but the company asked me to reimburse them for the cost (about $675 IIRC). Kinda tacky but also, kinda necessary from the company's point of view. I never did use the ticket.

It goes the other way too...the last company I quit agreed to pay all non-accrued expenses after I left. IE, there were items I had paid for during my tenure there in the remaining weeks that I either hadn't been billed for or had not submitted to accounts.

They asked me to reconcile within 2 weeks all of my outstanding expense items and then issued me a (quite large) check for the amount. Fair is fair.