In any city or town which accepts the provisions of this section the widow of any employee who was killed, or who died from injuries received, or died as the natural and proximate result of undergoing a hazard peculiar to his employment, while in the performance of his duty, and whose death occurred prior to the effective date of any law providing benefits to his widow, shall be paid an annuity in the amount of two thousand dollars so long as she remains unmarried.
The provisions of section eighty-nine C shall not apply to any city or town which accepts this section.