If the gross receipts are from business, the trust need to get the accounts audited u/s 44AB. Rule 6G of Income Tax rules provides as under:-
6G. (1) The report of audit of the accounts of a person required to be furnished under section 44AB shall,—
(a) in the case of a person who carries on business or profession and who is required by or under any other law to get his accounts audited, be in Form No. 3CA;
(b) in the case of a person who carries on business or profession, but not being a person referred to in clause (a), be in Form No. 3CB.
If the trust is not required to get the accounts audited under any law (this could be state specific) then the audit report should be in Form 3CB.