Many partners, friends and colleagues will eventually find themselves giving a helping hand to a person with ms. It is all too easy to rush in and try to help (in my case with a fridge the first time I wanted to be useful) only to find that you hurt your back. Helping someone up off the floor is a classic and the advice from physiotherapy departments is "don't do it" which is unhelpful!!!
My advice is to let someone that has fallen calm down and relax a bit before trying to get up and then get a chair for them. Put the chair in front of them, ask them to kneel in front of it with their arms on the seat. Get them to relax there for a minute or so and then kneel up, bring their good leg up with the foot on the floor, take a couple of good breaths (to energise them again) and then push up with their arms and the good leg. If necessary be ready to steady them as they get upright but let them take their time before trying to twist around onto the seat.
I use this method to help my clients up off the floor after a session and will try to take some photos at one of the next classes - I promise I have never left anyone on the floor after a class