Tricky. What *I* would do is make an evaluation of what price she is indeed locking up, and ~IF~ it is reasonable, I would accept and chuck it up to experience. ~IF~ it is not, decline and give the reason that makes the most sense. Is there one decline option - "Prices not set yet" or something like that?
BTW, Airbnb opens up host calendars and makes future bookings possible in monthly increments, not sure the criteria they use or if uniform among all hosts. My October 2020 calendar is just opening up, so guess the limit is 3 years. The 'wrong price' thing tends to happen often, when passed prices are used by them automatically; understandable since they have nothing else to go by.