Help: Overstressed and Unsure (FINAL INTERVIEW)

I am in my third year currently seeking my second placement. I have managed to land a final interview at a big firm for an equity research position - the recruitment process consisted of the first interview, written test, and a modelling test. I presume I did well on all three as I have been called in for a final interview.

Today I received an email from my coop coordinator saying that "they are looking to move to an offer for you, but they are waiting to get final approval from the Head of Research."

My coordinator asked if she could present the offer to me even though it was still tentative, the person said yes absolutely that is no problem. This is where things get tricky.

For a second I was relieved and happy as it has been stressful and I had finally gotten a job. However, I then received another email stating that the firm wants to schedule a final interview with the MD, Head of Equity Research.

I guess my question is, have I been picked and the firm jus needs the MDs blessing and him to like me before they can go ahead and officially hire me? Or are there 1/2 other candidates as well in the final interview that I'm up against?

This has been really stressful and was hoping for clarification as I would really like this job.

Thanks in advance.