I'd use the same idea in the justice system, where the presumption of innocence is paramount, and apply it here. It's better to let 9 criminals go free, than to jail 1 innocent person by accident, and it is better to assist 9 extra people in need, than to let one person in need to not get it due to the rules.

Somebody needing assistance is presumed to need it, until proof is found that they are cheating the system. This will let some people use the system fraudulently, but it ensures that it catches the vulnerable that truly need it.