@Karen783
I am so sorry and please under no circumstance initiate the cancellation.
If your end goal is to have this reservation cancelled you can ask her to initiate the cancellation process and you would communicate for airbnb to issue her a full refund- this way it is a mutual cancellation.
Realistically she should cancel and any monies lost should be covered by her travel insurance.
In the case you want to play hardball just say that all cancellation processes and fees are handled directly by airbnb and ask her to please let you with plenty time as to be able react accordingly.
Good luck to you. 🙂