I use malwarebytes, the only one from your list I do use.
It was easy getting them to talk to each other. 7 computers (more actually, those are the windows ones) doesn't matter, of course, it is the OS's they're running. Being all from the same stable you'd expect them to communicate alright. Being MS you wouldn't be so sure. But in fact they do. There's only XP, 7 and 10 and until last week it was only XP and 7. See? Simple really.
The NAS could be any one of those computers and that's the plan.
But that's not the question really. That's offline storage for emergencies, essentially, isn't it?
For every day use we want 7 computers on the LAN with all their attached Hard Drives available to all. Well available to me anyway, Admin. That's something like 20 Hard Drives.
I don't want ransomware getting into the LAN and encrypting 20 drives.
It has been indicated to me that they only encrypt certain files - obviously your data files. Well that would be all video and image files and audio files, I guess. Then all document files, too. Then perhaps all saved html.
Prime targets would be My Documents, My music, my audio and so on.. And IIS. My IIS directories and data being very important to me and necessarily alive all the time and frequently altered.
Seems to me a good tool could be an automatic compression utility that saves all such files in some compressed format every time you save them and thus makes them of much lower profile to the ransomware - they may even pass unnoticed.
In my case I have many gigabytes of such data. So much that the only way to keep it is on Hard Drives. DVD's would be hopeless. Tape drive would be good. I don't like the cost. But tape is back again and the offline medium of choice, I think.
But though I've got much and I want it accessible all the time most of it is, of course, relatively ancient. Static. I can copy it off onto some Terabyte drives and try to keep them offline. There's the NAS.
But the question is really about using MS's sophisticated file permissions scheme. I mean, that's what it is there for isn't it? File protection. It is possible for even admin to be blocked from altering a file, accessing a drive.