The Nationwide Luxury Cruise plan is designed for travelers that will be going on longer, more expensive cruises. Coverages include Trip Cancellation & Interruption, Optional Cancel for Any Reason (if eligible), Medical, Emergency Medical Evacuation, in most states an Itinerary Change Inconvenience benefit and other cruise specific benefits.
To learn more, see the Nationwide Luxury Cruise product page.
"All premium is non-refundable after a ten (10) day review period from the date of purchase in the event You have not incurred any claims during that time. In the event the premium paid for coverage is less than the required premium for coverage, benefits will be paid in direct proportion of the actual amount paid to the required premium due."
Since your husband was insured under this Nationwide policy from 11/17/2017 up until the day he decided to cancel, his premium was considered earned and nonrefundable.