Answer:
Either one is possible:
b. will need
c. needs
Step-by-step explanation:
In the case of 'needs,' -- when using either-or constructions -- If one subject is singular and the other is plural, and the words are connected by the words "or," "nor," "neither/nor," "either/or," or "not only/but also," use the verb form of the subject that is nearest the verb.