They are swamped right now with similar requests, @Kristy145 . You could try Twitter. It's AirbnbHelp you want there.
Very sorry about your mum. Hope she recovers soon.
You don't have to do this, but if you are in any position to leave things as they are, you might consider it. You and your host each bore 50% of the cost of something neither of you had any control over, and that sounds fair to me. But I'm a host, so you don't have to listen. ; ) None of my guests have offered 50% either, but most have promised to rebook sometime in the future.
All the best, whatever you decide.