If it says to resilve a die showing ranged damage, am i allowed to resolve a ranfed modifier as well?

When something says to resolve "a die", it means just that - a single die. You can't add a second die with a modifier to it, and you can't resolve a single die that just has a modifier (unless you're playing the "Legacies" card, which specifically says to resolve a modified die by itself as if it didn't have the +).