In the event the State Senator or a member of the House of Delegates of Prince George's County dies during his term of office, beginning with the session opening in January, 1963, the Council shall pay to the surviving spouse of the deceased Senator or Delegate such sum as will equal the amount of money he would have received from the State had he lived until the end of the year in which he died. If there is no surviving spouse such sums shall be paid to heirs at law of the deceased Senator or Delegate.