There are many private vans with pick n drop service, but you have to search for it...the best way for it next time when you go for dropping down your kid, stay there for a while...hopefully you'll find one of them...or if you have some other schools nearby, you can find some vans there but they are private and don’t have any organized system for contact.
Sometime query with the school management would be helpful for sorting out conveyance problem as they have some van's contact numbers :)