I'm not a host but a guest with many long term stays, and 25-year work history in customer service at a variety of levels.
I think she did the emotional dump to try to convince you to take responsibility for her problem. She could have read the news about how the fires have impacted LA, read about there not being AC in the listing, and read the cancellation policy. I think perhaps in considering meeting her halfway you're lowering your self-protective boundaries out of unwarranted pity and fear of the power of the review. You don't need to water her yard if it's dry, it's her yard. She doesn't care about your yard. Maybe her employer will cover the expense, but it's not your responsibility. I'd say trust your gut about her sense of entitlement and not feed it.
If she leaves a bad review, you can be honest and sincere in your response and that will shine through. You also can leave her an honest review toward the end of the two weeks that says she didn't want to honor the cancellation policy when her leaving had nothing to do with you, didn't even ask if you had a fan.
People are allowed to ask for something and try to convince you to agree, and you are allowed to say no.