Dear Rabbi Simon,
Suppose someone feels unwell on Friday night/Shabbat morning and calls Hatzola. They decide to transfer the person to the Royal Free (A&E) and the husband/wife accompanies the patient in the ambulance. After some tests, the doctors discharge the patient but tell him/her to take medication and rest. Does the patient, who obviously cannot walk back home, have to stay in hospital till motzei Shabbat or would he/she be allowed to go home by minicab (called by hospital reception of course)? What about the husband/wife? Can they also go home in the minicab or do they have to walk home?
In most cases, it is possible to avoid melachah min ha-Torah in riding in a car (or other vehicle) on Shabbos. This being the case, I would say that one could accompany one’s spouse in the car if his/her presence would be helpful or reassuring to the patient. If, however, there is no compelling need for him to assist her (or her to assist him, as the case may be) the robust spouse should stay or walk.
Best to limit medical emergencies to weekdays, but this is not always possible!