With very high volatility (as there was in Dec end) it is extremely risky to go for naked shorts. A covered short would have worked much better for you.

You shorted one Mini Nifty Feb Future @4742 and other @4775.
Now you had a exposure of -40 units @4758.

Suppose you want to keep a stop loss and buy an out-of-the-money call option of 4800 for 50 Rs premium (say). So total outgo = 50X40=2000.(option premium)

Now there are three possible scenarios.

A) Nifty Feb expires @ 4750

Profit from Futures = 8 X 40 = 320
Loss from Options = -2000 (Options expire worthless)
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Net P&L = -1680


B) Nifty Feb expires @ 5400

Loss from Futures = -642 X 40 = -25680
Profit from Options = 600 X 40 = 24000-2000 (premium amount)=+22000
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Net P&L = -3680


C) Nifty Feb expires @ 4400

Profit from Futures = 358 * 60 = 21480
Loss from Options = -2000 (Options expire worthless)
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Net P&L = 19480.

So using this strategy your downside is limited to max 3680 Rs loss while you have unlimited upside ( 19480 in this case)