Had a toilet plumbing leak, what percentage refund to give?

[Vernon42]

It is the first night for a guest in our airbnb. they will be staying for 4 nights. At 1130pm she contacted me saying the toilet was running across the floor. I went to look at it and it looks like there is a leak at one of the pipe seals. I immediately called a plumber I know and he said he could come out tonight but she is tired and wants to wait until the morning. I want to give her some sort of refund for this night because of this issue. Should I refund a percentage of this night or just refund the whole night? I want to make my guest happy and this stay has started off on the wrong foot because of this. 

[Mike-And-Jane0]

@Vernon42 we had a similar situation where a guest was disturbed for one night. No big deal made of it but we felt we should do something. As the property was not booked back-back we offered an extra night stay free of charge. Effectively no cost to us and it was very much appreciated by the guest.