Agreement between Commissioner and State; contents

that such payments will be made (subject to subsection (c)) to all individuals residing in such State (or subdivision) who are receiving benefits under this subchapter, and

such other rules with respect to eligibility for or amount of the supplementary payments, and such procedural or other general administrative provisions, as the Commissioner of Social Security finds necessary (subject to subsection (c)) to achieve efficient and effective administration of both the program which the Commissioner conducts under this subchapter and the optional State supplementation.