Section 25. Whenever it appears by a valuation certified to by a competent actuary that the actual assets of a society exceed its liabilities, including in liabilities the tabular reserves computed on the basis specified in section twenty by an amount equal to five per cent of said reserves, increased by an amount equal to all its other mortuary liabilities, it may, by vote of its officers having the powers of directors, and for such period as its assets are maintained as aforesaid, waive the further collection of the regular mortuary contributions from its members. A society maintaining a surplus of assets in excess of such amount as enables it to waive contributions as aforesaid may pay back to its several members an equitable portion of such surplus in such manner as may be determined by vote of said officers.