After thinking about this some more:
I think almost everyone has forgotten a couple of very important things -
Is Grandma still using her stuff?
Can she find what she wants when she wants it?
Does she want help with folding, etc? or at the very least, is she willing to accept help?
Have you asked /offered to help with getting her space back in order?
I think I would accept help IF OFFERED and I had a chance to say yes or no.
I also think I would be very annoyed (p*ssed off, is what I really would be) if someone just came in and started messing around with MY stuff while I thought I was very capable of still doing it myself.
If someone came around and said - "Would you mind if I refolded some of these things for you while we chat?"
that comes off a lot differently than
"This place is a frightful mess and I am going to step in and take over reorganizing it for you because I want it to be orderly when you croak."
I think it would be good for you to do this together - if possible - if you do it - so she has some idea of where to find things after they have been rearranged.
My Mom and Aunt thoroughly cleaned their Mom's house (my grandmother) while she was hospitalized with a broken hip. They put things back approximately where they were - but they did have the NERVE to throw out things like empty dog food bags (after checking them to make sure there was nothing stored in them) - Grandma was ANGRY at them about the whole thing for a long time.