You probably already know this as an experienced Superhost but if you aren't able to host your guests contact because of unforeseen circumstances ie a boiler breakdown, a fire at your property, unexpected guest damage flooding etc you can use the host EC to cancel penalty free upon providing evidence.
Airbnb will then help your guests find alternative accommodation @Temple5
You can help your guests by doing a search for comparable places locally and share this information with them.
Do let them know straight away to help them maximise their chances of finding a suitable alternative.