Personally if I have to pick one it’d be A. Sometimes, especially with a random team who hasn’t quite meshed yet, stuff is just gonna go wrong and cause a wipe. Losing points towards the final score makes sense - many games with point systems have you lose points when you die. Losing out on credits, XP, or gear feels a lot more punishing, unfairly so, and could result in people very quickly ‘dodging out’ of groups they consider unskilled without finishing the mission, or just not participating in the random queue at all.
Credits, XP, and gear are all rewards just for playing the game. Final score points are the only thing in this list that I personally feel should be should be directly tied to performance in a specific mission.