Occasional Babysitter for 1 Child

My son is with my mom 5 days a week, I just need someone to go to her house in Ashburn, to watch my son along with her, "to help her out" for maybe 4-5 hours a day . you can do 5 days a week or 3 days a week. I am willing to pay a set weekly rate of $150 weekly, for 4 hour a day for 3 days a week. If it works out, pay rate can go up.