after doing b a and llb (3years) i am eligible for net exam or not
As per the NET eligibility criteria, a person need to have completed a Masters in the discipline wishing to appear as NET paper/subject. So as you have BA and LLB degree but you haven't completed the MA course, you aren't eligible for the phD programs through NET.
For more information regarding UGC NET consider the link below:
https://competition.careers360.com/articles/ugc-net-exam-dates
For the official website consider the link below:
https://www.ugcnetonline.in/eligibility.php
I hope this helps. Wish you a great eve!