In the event of the death of any clerk who has not retired under any of the provisions of this chapter, but who was eligible to do so, the surviving spouse shall receive a monthly sum during his or her lifetime equal to 50 percent of the amount such clerk would have received had he or she retired under subsection (c) of Code Section 47-14-70. In order to receive such benefits, any such spouse must be at least 55 years of age and have been married to such clerk for at least six years immediately preceding the death of the clerk.