Alreration

[Valentine6]

My guest refuse to accept my 1 day alteration despite my very generous refund offer.....

[Amaris0]

Do you mean you would like the guest to arrive a day later or leave a day early? If so, whilst your offer might seem generous to you, it might not actually fit in with the guest's plan, therefore not a generous offer to them. 

If you are both unable to reach an agreeable solution and the alteration as is as a direct result of your making, then I'm afraid you might be left with no choice but to cancel and take the penalties; if the guest can't accommodate your changes and they cancel they will be stung by your strict cancellation policy which is unfair to them.

I hope you can sort out something between yourselves.

Ama

[Miki--Pronounced-Mickey-0]

I am wondering if you could offer to find and pay for alternative accomidations that are equal to or better than your place for the one night? 

[Amaris0]

Not really as that would be third party booking which Airbnb do not allow.

[Ed-and-Hugh0]

@Valentine6 If they don't want to accept your refund, you cannot force them to do so. Just enjoy the extra cash.