One of four people can make the decision in most jurisdictions:

 1. The patient themselves, if they are of sound and reasonable mind
 2. The patient's next of kin, if the patient is not able to make the decision themselves
 3. The patients enduring power of attorney for health, and they can override the next of kin's decision on this
 4. The doctor themselves, if they determine that a resuscitation attempt would not provide meaningful quality of life for the patient - they can, but typically do not in most cases, override the above threes decisions (e.g., there's no moral or ethical reason to resuscitate a 100 year old severely demented individual who is bed bound, even when the family demands it)

In your case, the difficulty is the "next of kin" aspect - who has priority here, the husband or the child.  That might take an actual lawyer to determine (but someone else might be able to chime in here).