; (B) the expiration of a rental assistance contract for which the tenants are not eligible for enhanced voucher or tenant protection assistance under existing law; or (C) the expiration of affordability restrictions accompanying a mortgage or preservation program administered by the Secretary: Provided further, That such tenant protection assistance made available under the preceding proviso may be provided under the authority of section 8(t) or section 8(o)(13) of the Act: Provided further, That any tenant protection voucher made available from amounts under this paragraph shall not be reissued by any public housing agency, except the replacement vouchers as defined by the Secretary by notice, when the initial family that received any such voucher no longer receives such voucher, and the authority for any public housing agency to issue any such voucher shall cease to exist: Provided further, That the Secretary may only provide replacement vouchers for units that were occupied within the previous 24 months that cease to be available as assisted housing, subject only to the availability of funds