Older Americans Social Isolation and Loneliness Prevention Act This bill expands the scope of certain grant programs and the duties and functions of the Administration on Aging to prevent, screen for, and respond to social isolation and loneliness among older adults. For example, the bill establishes an advisory council on social isolation and loneliness to evaluate efforts to address these conditions and directs the administration to update certain best practices for home-based and community-based ombudsman programs.