raleigh c200
 

it has shimano fh-mc18 rear hub
i was wondering if i could put disc brakes on it

I can't find a non-drive side picture of it. Just have a look and see if there are disc brake mounts on the fork and at the back on the frame. My guess is no.

edit, your hub has no mount for the actual disc.

Not worth it. Need new hubs, adapters to mount the rear brake caliper, a new front fork with caliper mounts (unless the mounts are already on the fork), and the brakes, rotors, and cables. The parts and labor of all this could exceed the cost of a new bike that already has disc brakes on it.

thanks