The correct option is
B will have found
The sentence indicates that the subject will complete the task of finding a job by the end of the year. Thus, the tense of the sentence is future(as it talks about the end of the coming year). Also, it indicates that the action is complete with respect to the future. Thus, the answer must be in future perfect tense.
Option A is incorrect. 'will be finding' is in the future continuous tense and not future perfect tense. Thus, using it will make the tense of the sentence inconsistent.
Option B is correct. 'will have found' is in the future perfect tense. Thus, it indicates that the subject's action of finding a job will be complete by the end of the year. Thus, it is correct.
Option C is incorrect. will be having'' is in the future continuous tense and not future perfect tense. Thus, using it will make the tense of the sentence inconsistent.
Option D is incorrect. 'will have been finding' is in the future perfect continuous tense and not future perfect tense. Thus, using it will make the tense of the sentence inconsistent.