IN case of options, 
Turnover is premium received on sale of option.
In case of future..
Turnover is net difference in purchase & sale value..(ignoring (+) and (-) sign)
Many individuals who are doing share trading along with their routine job….they do not waste much time in tally accounting for their each contract note…they leave the turnover detail with their broker and do not carry it to their tally but they account for only net profit & loss…..but if you wish, you can account for each contract note to do proper accounting for your share market trading….hence to account for turnover in your tally,,,you may do following entries..
At the time of buy of option :-
Purchase of Option  A/c Dr. (Under purchase Group)
Option exp. A/c Dr. (Under direct exp.group)
To Bank/Zerodha Trading A/c(as per your transaction)
 
At the time of sale of option A :-
Bank /Zerodha trading A/c Dr. 
Option exp A/c Dr. (Under direct exp Group)
To Sale of Options A/c Dr. (Under sale Group)
At the time of buy of future contract:-
 
Future of XYZ A/c Dr. (Under Purchase Group)
future exp A/c Dr. (Under Direct Exp Group)
To bank/zerodha trading a/c
 
At the time of sale of future contract:-
 
Bank/ Zerodha trading A/c
Future exp A/c Dr. (Under Direct exp Group)
Future Turnover -loss A/c Dr. (if loss) (under Sale Group)
To Future of XYZ A/c (Under Purchase Group)
To Future Turnover- profit A/c (if profit) (Under Sale Group)
 
Turnover of option is given by Ledger “Sale of options A/c”
Turnover of future is given by Total of Two Ledgers “Future Turnover -loss A/c ” &  “Future Turnover- profit A/c”. First is having debit balance and second will have credit balance. hence these cannot be added up in tally. But we have to manually total them to find future turnover. 
Future of XYZ a/c is already nullified by debit & credit entry as above. 
Coming to your second question, your turnover is 26 Lakh and you are having loss in trading then…
Your turnover is below 1 cr but you have to see one more thing i.e. have you opted for 44AD and then opted out of it before completion of 5 year…IF yest then you are required to go for audit to claim loss.
IF NO then you are not required to go for audit. 
for more detail
CLICK HERE