Don't worry about the extra ticket if she doesn't come along. All that matters is that the day itself is about fun. Hopefully she'll make it and we'd love to see her there; but it not, it'll be just fine.
If you've already told her about the tickets, please make sure she knows there's no pressure about showing up just for the money's sake. It should be about happiness and smiles or not done at all. What happens is completely in your hands.
Haha awesome dude. And I promise this was sheer happenstance, we didn't organize this or do it on purpose. The people we originally bought the tickets for bailed on us, so we're literally just sitting on these things.
And seriously how often do we get to meet or comic con happens? Spending forty bucks on this is a small, small price to pay and I'd do it one thousand times over. :) #yolo