Capital receipt or cap gain - dillema

Dear Friends,

One of my client has received a certain sum to evacuate a residential property where he was residing since 1974 as a tenant.

Now, this receipt shall be considered as Capital Receipt or is offered to Cap Gain?

If its Capital Gain then how the benefit of Sec 48 (Indexation) be availed as the client is not the real owner, what are the remedies available then?

Thanking you in anticipation