The correct option is C The antiques had not been kept by me in dad’s cupboard.
The right answer is, ‘The antiques had not been kept by me in dad’s cupboard’. In passive voice, the receiver of the action ‘the antiques’ comes first in the sentence. It is followed by the helping verb ‘had’, form of the ‘be’ verb ‘been’, the past participle form of the verb ‘keep’, ‘kept’, the preposition ‘by’ and the doer of the action ‘I’ which changes to object pronoun ‘me’ followed by ‘in dad’s cupboard’.