Good morning!

Compost mulch could be a good option - it will break down faster and create a more welcoming space for weeds to become established. 

Are you using the mulch as a way to prevent weeds from getting established or as a way to hold moisture in around the plant more?

Here  (and a second one linked here) are great resources on ideas for landscaping with fire resistance in mind. There is not information on types of mulch but there are ideas for a groundcover plant to put in that area!

Hopefully this helps - please feel free to ask more questions!

Rachel