Final answer:
The nurse should give a bed bath with complete assistance to the client who has a fever and experienced significant diaphoresis during the night.
Step-by-step explanation:
Given that the client has a fever and experienced significant diaphoresis, it would be best for the nurse to provide a bed bath with complete assistance. This will help the client feel refreshed and clean without exerting unnecessary energy. Bathing in the morning can also help the client wake up and feel more alert.