@Christi3 don't cancel yourself as you will be penalized by Airbnb. Here's a helpful Airbnb article on the subject of cancelling or altering a Long Term Stay:
I wouldn't offer a refund, but if they asked, I'd consider how likely I'd be to fill those nights. For example, a month rental might be $2800 but three weeks $2400. Would I be able to rebook at least three of the ten nights to make up the difference?