If the death benefit if from Social Security, it is not taxable. If that is the only income a child/dependent has, then the child/dependent does not have to file or report it either.
If the child/dependent has enough other income to be required to file, then the child reports the SS on their own return. Please see this TurboTax Help article: Do I need to file my own taxes if I'm a dependent?
@ckenealyl
