Do I owe a person who canceled a trip I organized a refund?

I organized a 2-week trip for a dozen students through my student organization. 1 month after I sent out the first flyer, I had collected deposits from all the participants.

Soon after that, the people at the destination advised me they had changed a policy thereby reducing the involvement of people on the trip for one day on one activity. I sent out a notice to everyone on the trip and offered to refund their deposits if they so chose. 4 people took me up and I promptly returned their deposits.

Now one of them is claiming I mislead her and her friend about the trip and I should be liable for her flight which she chose to cancel. I was not responsible for picking out the flights, I only arranged the trip. Once I offered to pay the cancellation fee of $187 she suddenly asked for $1,200.