There is a time outside of the open enrollment period during which you and your family have a right to sign up for health coverage. In the Marketplace, you qualify for a special enrollment period 60 days following certain life events that involve a change in family status (for example, marriage or birth of a child) or loss of other health coverage. Job-based plans must provide a special enrollment period of 30 days.
You can go to healthcare.gov to see if losing your coverage with your husband, because of his retirement from work, is a qualify event. If it is, it seems Nuance has to give you 30 days from that date to enroll in their plan.
I don't know what Nuance charges for employee plus 1 insurance, though.