The subject of a sentence is the person, place, thing, or idea that is doing or being something. We can find the subject of a sentence if we can find the verb. In the given sentence the verb is 'need'. The people who 'need' is the subject of this sentence. Therefore option B, 'we', is the correct answer.
Options A, C and D are incorrect answers because they are not the subject of this sentence, rather, they are the object, the independent clause and the adverb.