Unless you advertise and offer a Hypo-allergenic stay (and premium price), I would do nothing.
Your home, your rules, your cleaning routine.
It is not in my interest to explain my cleaning routine/choice of cleaning products with guests.
My answer to mold/allergy requests is to say "I'm sorry I cannot guarantee your health in my home" I'm not a Doctor, biochemist or psychiatrist and have no need to expose myself to a lawsuit.
If they give timely notice (they cancel sooner than later) I will refund them.
That said, I don't have mold in my home. I don't use air fresheners and do keep air circulation in my house.
Keep it simple