@Gay1 Oh dear, I am sorry Gay but, you are going to be on your own on this one! Sure commonsense would possibly tell a person to roll the grill to a safe location but, it was up to you to make sure they are instructed to do this.
You should have a laminated sign hanging somewhere very visible on the grill where it will not catch alight and on the wall instructing guests to roll the grill out from under the eave before using!! Sorry Gay, it's tough but really, you should have seen this one coming!
The thing that does really concern me, and you alluded to it, was how lucky you were that the property did not catch fire. I sincerely hope that you have a properly designated hosting insurance policy in place and are not just expecting that your regular household insurer will cover you in the event of something catastrophic like what could have happened here.
Almost all insurance companies will cancel household insurance policies if they have knowledge that short term rental is taking place in their insured space.
For details of appropriate cover I would suggest one of the two options......
www.proper.insure/ This company has had some good posts on the CC.
www.cbiz.com/insurance I know nothing about this insurer but, posts suggest they are active in this field.
Once again, what a terrible thing to happen to you Gay, it must have given you an awful shock. I just hope it will sort out without too much expence but, unless you have a 'Security deposit' set and report the incident within 48 hours of the guests departure, there will be little, or no avenue of compensation through Airbnb and, owing to the nature of the occurence I doubt that they would get involved anyway.... Try to protect yourself for the future Gay.....Rob