Am I wrong for being mad about this?

Sooo, my grandmother called me this morning and I told her I was going to school to study. My classes are on MWF's so Tuesday's and Thursday's are for studying math.
She said that if I am studying like I said I am [which I really am] then I need to tell someone [I don't know who] that I am not doing well in school.
I have only had one math test so far and I made a 74 and she said I should have made a 84 or 94. It was one test! Instead of supporting me she is being negative. My aunt that I live with also has been acting like she doesn't believe me either. For example today she asked me if I was going to school and I said yes....cause I have to return some books to the library anyway. She said your going way over there for that. I was like yeah I'm going there to study anyways.

Back to my grandmother--After upsetting me about my grade she then tells me that the money that I have left over from my financial aid she was thinking about leaving it in her savings account until I need it for the school that I transfer to since she will already be helping me pay for school. I know that my aunt told her to do this because she always tells me that I should let my grandmother hold my money like I am not responsible enough. I am 19 years old and I never ask my aunt or anyone for anything. I manage my money well. I have a savings/checking account and I have a job.
What should I do about this situation. Should I just let it go, speak on it, or wait until they bring something up again about any of this?

You should sit them down and explain to them that your 19 years old, and very well capable of handling your own money. As far as school goes, agree that yes, you could have made an 84 or 94 on the test, explain no one is perfect, and at least a 74 is still passing. Let them know that you are doing the best you can at the moment. :)