The correct option is A Didn't come
'Didn't came' cannot be the answer as didn't is never followed by the past tense form of the verb. 'Hasn't come' is in the present perfect tense and this would have been the correct answer if the second half was also in present tense i.e 'because he is sick'. 'Hadn't come' to work today is not appropriate because we use past perfect tense when we talk about two events happening in the past, one after the other. Here we are giving a reason for something that did not happen in the past, so the correct answer will be 'didn't come'.