Babysitter Needed For 2 Children In New York

We are looking for afterschool care for our two boys, L (7) and R (4), We need someone to pick them up from school, take them to activities in the neighborhood, help with homework, empty their backpacks and feed them dinner. This would be hourly work, but we would guarantee 20 hours pay per week (even when you are not needed because we are away or one of the grandma's wants the boys). We are looking for someone reliable, regularly available with some flexibility to occasionally stay later / put them to bed.