@Jose9762 Unfortunately, as you already pointed out, it is the responsibility of the guest to fully read the listing which includes the cancellation policy. When confirming a reservation you are agreeing to that policy. The only time this can be overridden is if your emergency falls under the Major Disruptive Events Policy, which I will link below.
Major Disruptive Events Policy - Airbnb Help Center
Here is what I would suggest, and what I offer as a host. I ask the guest to cancel, and if I am able to rebook the dates, I refund them for the rebooked dates. Perhaps you can contact the host and see if they would be agreeable to this.