Which verb moods would be best to combine in an essay on what life would be like if all wars were ended?

The answer is conditional and subjunctive moods.

The conditional mood is used to talk about improbable situations and  circumstances which depend on some condition.

For example: If all wars were ended, the world would be a happier place.

The subjunctive mood is used to describe wishes and hypothetical conditions.

For instance: I wish all wars were ended.

yeah, i think its a good thing what do you think?

d is the best answer for this question.