How much would you pay....

Ok. So I'm going to be starting a job after Thanksgiving. It will be part time 10 a.m to 3 p.m. 5 days a week.

I'm going to ask my sister in law to watch my 5 year old daughter at my house. She will have her 2 year old and 4 month old with her. I would have to pick her up and take her home (which is about 10 miles each way out of my way but she does not have a vehicle)

What would you pay her? Reasonably. Never had to do this before. I've been fortunate enough to be a stay at home mom.