The nursing home in which your husband resides should have a plan for sheltering and/or evacuation in the event of a disaster. In most states, the regulatory agency for nursing homes and other residential facilities requires the facility to have evacuation and sheltering plans in place. The facility or the regulatory agency should be able to provide you this plan in writing.
In the event of an evacuation, many facilities should know or have a plan where they are going in advance; evacuation sites are pre-determined. Again, the facility or the regulatory agency should be able to provide you with this information.
Make a point to request this information prior to an emergency or during the admission process. In addition to requesting a copy of the evacuation plan, find out what your role as a caregiver will be in the event of an evacuation. Should you go along? Are there special things that you should do to help the evacuation? The facility should be able to help you identify your role in the evacuation process.