Because the guest booked long term (30+ days) she falls under AB&B's long term cancellation policy which reads:
"If the guest books a reservation and decides to cancel the reservation during their stay, the guest must use the online alteration tool in order to agree to a new checkout date. Regardless of the checkout date chosen, the guest is required to pay the host for the 30 days following the cancellation date, or up to the end date of the guest’s original reservation if the remaining portion of the original reservation is less than 30 days."
Therefore, if she is now leaving with only two weeks to go, she should make the alteration to clear your calendar, but she would also not receive a refund.
Here is the link with the full policy:
https://www.airbnb.com/home/cancellation_policies#long-term