There are several accounts of people with severe MS being cured when hit by lightening or electrocuted.

Not saying they should stand out in a thunderstorm but it does suggest that electrical stimulation has some value. Even Edgar Cayce suggested electric stimulus.

Bee venom has also been used to some success.

My strange opinion is that it is a yet un-diagnosed food allergy for certain people with that genetic disposition. I think this explains why the symptoms tend to come and go in MS patients. This is not an allergy like most people think. This is a genetic inability to process some basic chemical in some food. Call it intolerance if you want.
A food diary along with tracking condition could indicate the offending food or chemical. I'm not suggesting things like diet coke but rather chemicals within whole foods. The chemicals in the foods of the nightshade family (potatoes,tomatoes, peppers)give me all the symptoms of asthma including the sleep apnea. I think it is genetic.

I have 12 brain lesions which Dxs can not explain.
I can only relate them to incidents when a food adversely affected me. As funny as it sounds, Stouffer's Creamed Chipped beef gave me a stroke when I was 24.

If your friends would do a deep dive into understanding what they are eating they may find the cause is something they are eating.

Before we became a world population people lived in small tribal groups and they knew what foods to stay away from because their elders figured it out and passed the knowledge on. Most of us are now genetic soup with no idea of what our ancestors identified as not good for us.

Celiac disease was discovered when there was a grain famine in Europe and people were eating potatoes instead. Those with Celiac Sprue suddenly thrived.

Certain Jewish genetic lines have MS like symptoms when they eat chicken.
Some people just can't eat Lamb.

The most productive thing your friends can do is start working on using "The Elimination Diet".
It can be difficult. I thought I was allergic to eggs but after years of working on it I realized it was the margarine I used to cook them. So everything has to be evaluated.

I would bet anything that they all eat similar foods and one or more of those foods is the offender. Seems too simple to be true. Sometimes, most times, simple is really the answer.

Zapping sure would not hurt.
Using Colloidal Silver would help to reduce the inflammation while they work on the diet.