Several hours after eating a chilled three-bean salad containing home-canned green beans, family members have difficulty breathing and swallowing, double vision, and muscle weakness. what should they do

I think what they should do is to go to hospital immediately because they may have botulism. This is because from the symptoms they such as difficulty breathing and swallowing, double vision, and muscle weakness, may be as a result of a botulinum toxin present in the food, and that can only be explained by a specialist doctor, who would give a reliever and determine the cause.