How much to pay an innsitter

We have to go away for a weekend. We have blocked off the rooms, but before we did, one person made a reservation. So we have one checkout on Saturday.
We have asked a friend to spend Friday night, put out breakfast and lock the door after the guest leaves. We will give the friend an inn room. How much do we pay her? She is not a professional innkeeper, but we know she will do a good job of watching out for breakfast and locking up.
Is there such a thing as 'the going rate?'

Half of what you're making on the room?
Do you know her well enough that some sort of other gift would be appreciated? Dinner? Massage?
If it works out well will you all her to do this again?

I couldn't tell you. This is not an innsitter situation, but a friend helping out. I probably would give her $50 and some simple flowers.

I'm with BD. It's probably not really "work" to your friend, and she's going to treat your business well, regardless. Take her to dinner or buy her a gift certificate. If it works out well, maybe you can use her for your vacations or other emergencies, and you can pay her then.

Though it may not apply in this case, I love the question, "Is there such a thing as a going rate?" I have no idea, so I am curious.

My suggestion is to have an open discussion on what your friends remuneration expectations are.
Also ensure you have a list of emergency contractors for eg. Plumber and Electrician on hand for your friend should something go wrong whilst you are away.