Check below to see the answer:
This is an 18th-century English riddle so you might have worked it out already. The common answer to this classical puzzle is “at least one”.
According to Wikipedia, all potential answers to this riddle are based on its ambiguity because the riddle only tells us the group has been “met” on the journey to St. Ives and gives no further information about its intentions, only those of the narrator. As such, the ‘correct’ answer could be stated as “at least one, the person asking the question plus anyone who happens to be traveling in the same direction as him or her”.