The correct answer is (b) 30 days.
Section 358 of the Code of Criminal Procedure, 1973 states that if a person is convicted of an offence and is ordered to pay compensation, but fails to pay the compensation, the court may sentence him to imprisonment for a term not exceeding 30 days.
The other options are incorrect because they are not the maximum default sentence that can be awarded in case of non-payment of compensation under section 358 of the Code of Criminal Procedure, 1973.