Suddenly for past few days i have started getting 100 GB of backup file in this eve.json.1-.backup format. Not sure why it started creating backup suddenly and why it is taking huge spaces.

It creates daily and each backup file is around 90 GB. Please can some one advise what do i do here.

This is unlikely Suricata creating these files, but sounds like logrotate. How did you install Suricata? Or how are you rotating log files?