Will UCSB rescind my admission?

Only the college can tell, but since calculus is an advanced course and you are taking it at another college, it probably wont affect your admissions. As long as your other grades are still at the levels, or close to, they were at when you were admitted you should be fine. I would talk to your guidance counselor as to what they think and if you should take the initiative and notify you college of your final grade in the cl if it is not good to explain why it is low. Make sure you really discuss this with your guidance counselor, as they will know what is best to do. Just keep putting all that you can into the cl to get the best final grade you can. Good luck!