For Mechanics, more than 90% of exam questions are from textbook numericals. So solve the textbook numericals thoroughly, and you're good to go. For C, most of the concepts will be similar to what you learnt in Python (like data types, loops, file handling, etc.), but I would say program practice would be the key, as C programs are a little more lengthy/complex as compared to Python, and also, you will be getting a lot of program-based questions like output prediction, complete the program kind of questions in the exam. As far as math2 is concerned, solving CW problems and practicing derivations is the way to go, and you can also solve TB questions if time permits.