End of Internship - Should I return?

Hi! I'm an underclassman at a target school, and I interned at an ER firm for the past couple months. My last day for the semester will be in the next two weeks, as I have final exams after that.

I have a part-time internship at a different firm during the summer. When I told the vp I work for when my last day would be, he said that i would be welcome to come back during the summer if I wanted to. I didn't say anything definite then.

1) I have an interview for a public finance internship coming up, but my last day at the ER firm will be two days after the interview, so I probably won't know if I got it or not by then.

2) If I don't get the public finance internship, I would probably want to continue working at the ER firm part time.

So . . .

- Do I need to tell my current VP whether or not I want to work in the summer by my last day? It was a "We enjoyed having you here, you did excellent work, I need to talk to HR but this is still open" kind of thing.

- If I'm just going to leave for 2 or 3 weeks to take my final exams, I don't think I need to do anything special. But if I leave before deciding whether or not to work at the ER firm in the summer, should I give a thank you note / gift on my last day for the semester anyways?

Thank you!