I have just completed my Masters from Mathematics.What jobs are available for me at ISRO?

Yes you are eligible for ISRO after completion of M.Sc in Mathematics. You are eligible to apply for Indian Space Research Organization recruitment's after completion of the Master's degree course. Post name and the specialization are given below. 

>> Name of the Job Post - Scientist/ Engineer (SC) in Mathematics or Applied Mathematics 

>> Qualification Required - You must have completed M.Sc in Mathematics/ M.Sc in Applied Mathematics 

For further details you have to visit the official website of ISRO to check-out the vacancy details.