I think the correct answer is the third one, "I made the best brownies today!"
An unreliable narrator is a narrator whose credibility has been compromised. Since you can't tell if this narrator credibility has been compromised from a single sentence but need a whole text to develop such incredibility, I say this is unreliable because the narrator is giving its own opinion of something he/she has made, and you can't rely on he/she being imparcial.
We, the audience, know that Lucy is only talking with Tom because she needs his car. Due to the fact that Tom is ignorant to this fact, the irony we see here is dramatic irony
