Are there any institutions in India offerring postgraduate courses in data science or machine learning. If yes, please specify if a bachelor in mathematics (i.e. 3 years) can apply in them ?
There is a PG in Data science conducted by Upgrad having curriculum and Certification from IIIT Bangalore.
Check BITS-Pilani programs: https://bits-pilani-wilp.ac.in/programmes-for-individuals.php. They have M. Tech courses for working professionals.