For supplements, there are a few main ones that are recommended for MS patients. Vitamin D is a big one. There's been some work trying to link a lack of Vitamin D with the development of MS. Some of this is based on the observation that the incidence of MS is less in southern hemispheres (more sunlight). Also, researchers were able to prevent and stop the progression of EAE in mice (I know, it's EAE, not a good model), by giving them does of Vitamin D. I emailed one of these researchers, and her recommendation was 1000 IU/day of vitamin D, plus 800 mg of calcium. My D level was below the minimum healthy level (I was at 23 ng/ml, min. is 32 ng/ml), so I've been doing 4000 IU's /day. There are trials to start soon looking at the effects of high doses of vitamin D on relapse rate. All of this makes me think there is something to vit. D.
Another big one is omega-3 fatty acids, like those found in fish oil. At least one study showed some benefit to taking fish oil. This study used capsules that had specific ratios of EPA and DHA. I wasn't able to find oil with the same ratios, so I just got what the local grocery store had, and take 5 grams/day.
I also take a B-50 complex each day. A few months ago, I had an episode where I got some bad burning pain in my legs. I was ready to have the nurse call me in a prescription for Neurontin. After some discussion on this site, I started trying high doses of Vitamin B. After a few days, the pain started feeling better, and after 1.5 weeks it was gone. Coincidence? Perhaps. But the B complex is cheap, so I keep taking it.
As to other supplements like Quercetin, NAC, Alpha Lipoic Acid, etc., you might want to read through old posts. You'll have to make a decision for yourself on which ones to take. But given all these other supplements, I don't really see the need for a multi-vitamin.