Colonel: He knows how to summit Everest so he has to go.
Chand: He has summuted before too so he has to go.
Arjun: Its his mission so he has to go.
Aakash: He is doing the documentary on Arjun so he has to go.
The Sherpa: Every mission to Everest needs a Sherpa so that's obvious.
That leaves Anjali as the odd one out as she is only on the mission as a dream which is a less important reason than the rest of them the teams.