Range is the difference between the lowest and the highest values .
For your cousin, the highest value is +6 and the lowest is -2.So the range will be : 6 - (-2) = 6+2 =8
For your friend the highest value is +3 and the lowest value is -3, so the range will be : 3 - (-3) =3+3 = 6
Your cousin has the greater range score.