I agree with fellow FTers that DXB is huge and the signs are clear.

Nevertheless, for some people who have never been in a big airport, it can be confusing. So, I may suggest, that OP's in-laws verify from time to time with uniformed staff, that they are on the good track, and how much time they still have.
Indeed, even seasoned travelers can have a wrong perception of time, not realizing that DXB is really huge.

I have family members who cannot understand why a train station needs more than two rail tracks : one to the big city, one from the big city ... I can tell you that these guys will never find the way out of DXB !