(a) issue to its members old age insurance contracts providing for the payment of the money due on maturity thereof either at death or upon the insured attaining any age not less than sixty-five years,

(b) in case the society has more than five thousand members in a life insurance department, issue to its members endowment insurance contracts providing for the payment of the insurance money to such members at the expiration of twenty or more years from the date of such contracts, or to the beneficiary or beneficiaries under any of such contracts in case of death of any of such members prior to the expiration of the endowment period, or

(c) grant such surrender values or other equities as are approved by the actuary of the society and authorized by its constitution.