Hello Anit. Yes, you can make a big career in finance with low grad score. Prepare well for CAT and other national entrance exams. Along with it, try and get some experience in finance field. Moreover, if you get a CFA or a FRM certification, you can overcome the impact of low grad score.
So, first get a job, then prepare for entrance exams, and score well, and along with it, prepare for certification. Since, you have interest in finance, you can easily get through the nuances of certification course.

All the best.