Firstly it can’t be 84lks for 78000 shares of Tata motors in 1 day. For that to happen stock must have moved Rs 100 in 1 day (Tata motors at around Rs 300). The Maximum it has moved is around 8 to 9 %. So the maximum loss in a single day would be around Rs 25lks. The 84lks is definitely an exaggeration.
If a client doesn’t have enough margin to hold a futures position, we square it off, this is consistent with our margin policy. Exchanges charge a penalty if F&O positions are held without enough margins. Some clients try to come back and get lucky if stock goes against and then comes back in their favor. Our risk management can’t wait for a stock to recover (which may or not may not happen) when market goes against a client and he doesn’t have sufficient funds.
Our margin policy:
https://zerodha.com/z-connect/tradezerodha/margin-requirements/zerodha-margin-policies