If a beneficiary is receiving the annuity provided through the School Employees Retirement System of the State of Nebraska or through the retirement system for Class V districts as provided by the Class V School Employees Retirement Act, the supplemental benefit shall be the benefit that would be computed under section 79-942 had the deceased retired person still been alive. The beneficiary will continue to receive the supplemental benefit until the expiration of the annuity option selected by the member.