The principle grants a right of private defence of body and property using reasonable force, but that right does not apply if the person had time to seek protection from public authorities instead. X learned at 5 pm that his crop would be burned at midnight, had a police station just a kilometre away, but did not inform the police, instead arming his family and fighting off the attackers around 11 pm.
Since X had hours of advance notice and a police station close enough to reach in time, the right of private defence was never available to begin with, because the principle withdraws that right whenever recourse to public authorities was a real option.
Therefore, the correct answer is X and his family is liable as they have not informed the police.
The fact that decides this question is time, X learned of the planned attack at 5 pm, had a police station one kilometre away, and did nothing to alert it before the attack came at 11 pm. That six hour window is exactly what the principle says removes the right of private defence, so every option can be tested against whether it accounts for that window.
Only the option that connects liability to the unused time and the nearby police station matches what the facts actually establish.
Therefore, the correct answer is X and his family is liable as they have not informed the police.