Kalyani

First of all I didn't understand your question, I mean if you are a diploma holder with average 50% marks and have secured a good rank around 50 then you can definitely take admission in KGEC, having maths or not doesn't matters, JELET is basically a exam through which students of diploma engineers can take admission into B.Tech colleges in West Bengal. So, if you are already completed Diploma or in last year then start preparing for it.
GOOD LUCK!

KGEC has better placements than JGEC as per previous records.

You will have score under 150 general rank and under 20 branch rank to get cse in KGEC.

Hi,
Eligibility Criteria:
Higher Secondary passed (10+2) with English, Physics, Chemistry and Biology
Percentage of Marks: At least 50% of mark in aggregate
Yes, you can apply.

I think, you'll get IT most probably and not CSE.

For admission in this course, you need to be a graduate with Honours in any Humanities/ Social Sciences/ Sciences.
You can apply online/ offline with the required information.

Kindly visit the academy in person and get the feedback from students.

What rank in JELET is required for taking admission in a government college?
Source: http://entrance-exam.net/forum/general-discussion/what-rank-required-jelet-take-admission-government-college-207990.html#ixzz24rDZ9Ir0
Source: http://entrance-exam.net/forum/general-discussion/what-rank-required-jelet-take-admission-government-college-207990.html#ixzz5RepfegbZ

You don't need to give the exam but in my point of view, you should opt for improvement exam because with this score, you'll not get anything- neither a job nor good colleges for further studies.

Hi Jyoti, Please refer to the link provided below for the detailed comparison:
https://www.shiksha.com/resources/college-comparison
You should be able to compare various features of the two institutes to help you reach a decision.