Question

under what condition can a body travel a certain distance and yet its resultant displacement be zero

Answer 1

If the body starts from a place and returns back to the starting point.
For ex. In a circular path around a park, if a jogger starts from point A, takes a round of the park and returns back to point A, then his resultant displacement will be 0.

Answer 2

if a body starts from the points come to the same point that he start so that displacement is be 0 like a man started running in a circular track come to the starting point