Should we buy food for the teachers that we felt like they bullied us during our internship?

Before we begin, I want to be upfront and admit that the university administration didn't handle the process of introducing us to the school where we will be conducting our practice teaching very well. Perhaps that's why the school staff didn't have the best impression of us.

During our internship, we were constantly compared to the other interns in the school. They questioned why we didn't apply to other schools and suggested that we could have learned better if we had enrolled elsewhere. One teacher even ridiculed my friend's makeup and kept bringing it up even after she stopped wearing it. We were uncomfortable when they gossiped about us in front of other interns.

To add insult to injury, they are now indirectly demanding that we buy food for them before we leave the school. They're implying that we can't just show up and leave without burdening them. This is ironic considering we've already done a lot of work for them during the past few months!

PS: We have already given gifts to our cooperating teachers.