(a) a refund of the contributions made by the member; or
(b) a monthly deferred vested retirement benefit, which shall be payable on his normal retirement date; provided he is then living, and on the first day of each month thereafter during his lifetime, computed in the same manner set forth in § 17-522, except that such computation shall be made as of his date of termination of employment; provided, however, that if the date of death of such member occurs prior to his normal retirement date, his beneficiary shall receive a refund of the member's contributions credited to such deceased member.