Mom's going crazy over my grade in AP Euro?

Okay, so I wasn't doing so great in my old ap euro cl (got about a D) and so I switched teachers. I got a high C on a test, which is really good considering my new teacher didn't give me notes, and I only had one day of that teacher's cl... and we watched a movie. Anyways, now my mom is giving me ABSOLUTE HELL. Yea, I got one of 3 C's in the cl on that test...but I DIDN'T HAVE THE NOTES/MATERIALS HE WENT THROUGH IN CL. All I had was 2 sections of Palmer. Now she's telling me that I don't deserve collage, etc. This is stupid, especially considering that last year I made a 4.0gpa in all honors. help?