Senior Hunger Prevention Act of 2023 This bill modifies and expands nutrition programs for older adults and adults with disabilities, including the Supplemental Nutrition Assistance Program (SNAP) and the Commodity Supplemental Food Program (CSFP). Under the bill, a household's eligibility for SNAP benefits may be certified for 36 months if all adult household members are elderly or disabled, an increase from 24 months. The bill also expands the SNAP medical expense deduction. The Department of Agriculture (USDA) must establish an elderly simplified application program (ESAP). Under ESAP, a state may implement a streamlined SNAP application and certification process for households where all adult household members are elderly or disabled and have no earned income. The bill also directs USDA to authorize public-private partnerships between USDA, retail food stores participating in SNAP, and community-based organizations to provide free or low-cost food delivery under SNAP, including through the use of private funds. Further, the bill reauthorizes CSFP, provides additional funding for the program, and expands eligibility to include low-income adults with disabilities. CSFP benefits may also be certified for 36 months. Currently, benefits may be certified for not less than one year, but not more than three years. The bill also expands eligibility for the Seniors Farmers Market Nutrition Program (SFMNP) to include adults with disabilities, provide a 36-month certification period, and include minimum and maximum benefit amounts. Under the bill, USDA must also establish various grant programs; for example, USDA must establish grant programs to modernize SFMNP operations and establish new farmers' markets.