Probably the best method is to rent a car from the CCC for the day, drive out and pick her up and use the car for other errands while you have it. I've read just a car service or taxi is the only methods of transportation. No shuttle bus.
We looked into Alleigant, but after adding the luggage fees, seat fees, there was no savings for us, so we stuck with our regular carrier out of Dulles. Plus our Alleigant flight would've gotten in at 10:00PM on a Friday night (only 2 flights per week).