She most definitely owes you for the ticket! She bailed for no good reason HOURS before the event? Barring any major emergency, which this doens't seem to be, she doesn't get a pass.
I had a friend who bought tickets (not pricy at all, under $20) for a local show, and as I don't see her often, would have paid her on the day off. Unfortunately, her stepfather passed away suddenly, and she had to fly across the country to be with her mom, and so we didn't go. I still paid her for the ticket, insisted upon it, even though it was due to her emergency we couldn't go. and she at first wouldn't hear of me paying her back.