Tenn. Code § 17-527
If the date of death of a member occurs prior to the commencement of any benefits provided by this chapter and prior to the first day of the month following his fifty-fifth birthday or his completion of eight (8) years of credited service or at a time that the member is under age fifty-five (55) and is not a judge, his beneficiary shall receive a lump sum payment of the member's contributions credited to the deceased member. If the date of death of a member, who was in the active employment of the employer on such date, occurs prior to the commencement of any benefits provided by this chapter, but subsequent to the first day of the month following his fifty-fifth birthday or his completion of eight (8) years of credited service, a monthly survivor benefit shall be payable commencing on the first day of the month following the date of death of the member. Such monthly survivor benefit, if any, shall be the amount payable in accordance with the option elected by the member as though the member has retired on the day before his date of death; provided, however, that if no beneficiary is living on the date of death of the member, a refund of his contributions shall be payable to his estate; and provided further, in lieu of all other benefits payable to a beneficiary upon the death of a member, the beneficiary may elect to receive a lump sum payment of the member's contributions credited to the deceased member. No death benefits shall be payable in the case of a retired member whose date of death occurs after retirement, unless the deceased retired member elected an optional form of benefit which specifically provides for a death benefit.
Notwithstanding any provisions of this chapter to the contrary, if a member is eligible for retirement or disability benefits, but dies without having elected an option, the beneficiary shall be entitled to receive a monthly survivor benefit in the same amount as the beneficiary would have been entitled had the member elected Option C of § 17-532, and retired on the day before his date of death.
T.C.A. § 17-527