The phrase "final stages" can have so many meanings. Honestly, I've not heard an actual neurologist use this terminology. But there are plenty of people asking a similar question that there must be doctors who say it.
Maybe you can tell us more about what is going on with your husband. Is he experiencing significant complications with his MS?
Some patients with primary progressive MS have a very aggressive and quickly progressing disease course. The progression for others can take many, many years (decades).
If you could share more about your story, maybe we could better assist you with information.