the first one is better! however, it would be even better to say "the third and final (question, point, etc) is..."

The third and the last

The third and last guys get a job. The rest of you, go home. The third and the last guy get a job. The rest of you, go home. . The third and the last samples are good. The third and last samples are good. . With "the" seems better on the last one.