Two months after decertifying the Franklin Public Library, the nation’s oldest, the Massachusetts Board of Library Commissioners restored its status last week. The library, which was started with a gift of books from Benjamin Franklin himself, had lost its certification in February when the state oversight agency determined that its budget had been cut a disproportionate amount, compared with other town departments, and failed to meet the minimum standards for a waiver. Town officials informed the state board Thursday that they had added $50,000 to the library budget for this fiscal year, according to Celeste Bruno, spokeswoman for the commission. Based on the new funding, the state commission voted to grant Franklin a waiver “with reservation,” and awarded the library $10,000 in grants, while opening the door to additional state aid, Bruno said. - Jose Martinez