"The college grant is non taxable"
That's not a valid, stand alone, statement. The scholarship may be non taxable, if it was used for qualified expenses. You don't have to use (actually only allocate) it to tuition, unless the scholarship is "restricted". That is, the conditions of the grant say it can only be used for tuition.
Being HoH doesn't change anything (kiddie tax rate will kick in later).
