The city or town councils of the various cities and towns may provide by ordinance for the freezing of the rate and valuation of taxes on the real and personal property located in the city or town of any head of a household who is one hundred percent (100%) disabled and unable to work as of the date of the disability; provided, that in the town of Hopkinton, the determination of disability must have been made by the Social Security Administration or the Veterans’ Administration, the applicant must meet income requirements established by ordinance which may be amended from time to time and may include the aggregate income of the applicant and all other persons residing with him or her and, upon attaining the age of sixty-five (65), the person who is totally disabled is no longer entitled to this freeze of rate and valuation; provided, that the freeze of rate and valuation on real property shall apply only to single-family dwellings in which the person who is disabled resides; and provided, further, that the exemption shall not be allowed unless the person entitled thereto shall have presented to the assessors, on or before the last day on which sworn statements may be filed with the assessors for the year for which the foregoing is claimed, due evidence that he or she is so entitled, which evidence shall stand so long as his or her legal residence remains unchanged. The foregoing is in addition to any other exemption provided by law; and provided further that in the town of Warren the exemption shall be in the amount of twenty thousand four hundred eighty dollars ($20,480), and provided further that in the town of Charlestown the town council may create a tax dollar credit reduction in lieu of such exemption, upon terms and conditions that the council may prescribe.