Upon the completion of the investigation the county department shall decide whether the applicant is eligible for assistance under the provisions of this article. The amount of assistance which any such person shall receive shall be determined by the county department with due regard to the resources and necessary expenditures and the conditions existing in each case, in accordance with the rules and regulations made by the State Department and, within available annual appropriations, shall be sufficient when added to all other income and support of the applicant to provide such person with a reasonable subsistence compatible with decency and health.