Converting active to passive voice means changing which noun is the grammatical subject, but the tense of the sentence has to stay exactly the same. Let's test each option by checking two things: is it truly passive, and does it keep the present continuous tense of the original?
Between the two grammatically valid passive options with the right tense, option 2 places the adverb in its natural position, making it the most appropriate passive construction. Option 4 is technically passive but reads unnaturally because of the misplaced adverb.
Let's summarize:
So the most appropriate passive form of "He is doing his job well" is "His job is being done well."