Company pareshan kar rahi hai

At what post were you working? As such after lapse of notice period, in private sector unless there is serious lapse, allegations have little value in eyes of law.

Did you have any prior notice/charge during service period?

Sir

I was working as a branch in-charge and no any prior charges or allegations against me.

If your terms of appointment contemplates one months notice period, then you have done no wrong. You are no longer to work for more than one month and you may also ask for full and final settlement like outstanding salary, leave encashment, bonus, gratuity etc.

I believe that company has somehow got the hint that you are starting your own project/ business and that is the only reason they are threatening you to send legal notice to you.

Sir 

Is ther any possibility after the notice period?