Well, if it was a rag-tag caravan, I'd imagine families, livestock and perhaps a few possibly-seedy-looking men-at-arms, hired for protection. If it's more of an official caravan, there'd be a few soldiers at the front and back, on horseback. Plus merchants, families and the occasional healer/doctor/medical type. If any of the caravan riders are royal, there'd be knights with them. Rag-tag, you're maybe looking at a dozen to three dozen people/children. Commercial, possibly fifty to a hundred, and if it's royal, you're looking at several hundred, a caravan that's miles long.
Educated guesses, though. Take them for what they are.