West Bengal

If you are from the general category, click on the below link:
https://www.shiksha.com/engineering/college-predictor-results?sg[]=112&sc[112]=39533&ect[112]=rank&gender=2&category=1&ds=127&sp[]=108&uaf[]=specialization&uaf[]=location&rf=filters
I have modified the search according to your preference except for location. I think outside Kolkata, Asansol Engineering College (Asansol) can be an option for you. In Kolkata, you may go for Neotia, Techno, JIS, etc.Find that below. https://www.shiksha.com/engineering/college-predictor-results?sg[]=112&sc[112]=39533&ect[112]=rank&gender=2&category=1&ds=127&sp[]=108&uaf[]=specialization&uaf[]=location&rf=filters&ct[]=130&tab=college
I would suggest going through the recent placement details of each college you apply for from their website. At the end of graduation, you would wish to go out of college with at least 1 job offer in hand. There are off-campus opportunities in IT nowadays but still on campus might help you get a job easier as competition is a little less fierce.

IEM Kolkata is one of the best private engineering colleges in West Bengal offering the best quality education and career opportunities to the students. Almost 100% of students got placements with good salary packages. The faculty is well-experienced and qualified here providing the best training and guidance to students during their studies and placements. Labs and classrooms are good and equipped with modern technologies. Good internship opportunities are also provided to students helping them to understand the challenges associated with the industry. IEM is doing very well in terms of placements and companies like Microsoft and Adore have a very good history with the college for placements. Visit the website:- https://www.shiksha.com/college/institute-of-engineering-and-management-salt-lake-city-kolkata-23742/courses/be-btech-bc.

If you are looking for best University for to pursue higher education, you should not be area or location specific, I would advise you to choose best University on the basis of University ranking, placements, infrastructure, faculty members etc. Mathematics covers a broad range of themes. Hence, you can choose any major field like Statistics Operations Management, Accountancy, Actuarial Sciences and many more. You can join academics after acquiring a Bachelors degree in Mathematics. Being a Mathematics student, you can pursue a career in data analysis which is currently in high demand. Mathematics provides a plethora of opportunities in almost all areas. There is a large basket of professions for a Maths graduate!
Scope in Higher Study:
Master of Computer Applications
Master of Business Administration
PG Certification in Data Science
Master of Science in Data Science
PG Certification in Machine Learning
PG Certification in Machine Learning & Deep Learning
Here are he best University for B.Sc. Mathematics-
Geeta University, Panipat
SRM University
VIT
Manipal University
Chitkara University
Chandigarh University
BIT Mesra.