Call NCL and cancel the cruise, they should give you a link to go to AON where you can print out forms, etc. One of them is for the doctor to complete. Then, send all completed forms off to claim.
When you cancel the cruise NCL will refund all except the base fares and insurance.
We cancelled a cruise a week before sailing in July 2019 when I developed severe medical condition, and we were able to claim all except insurance and what NCL refunded.
Sorry to hear about your wife’s accident, hope she’s as comfortable as can be and continues to recover well.