A is a Crud RoadRacer, a favourite when there's little clearance.
Where I live mud is a constant. As the rear guard covers a lot of territory there's plenty of scope for friction, especially with so little room beneath the brakes. The Crud that used to be in back needed frequent adjustment. I preferred something more grounded. My solution is a SKS guard in two pieces,
B and
C.
B is zip-tied in two places (three if you count the zip-to-zip action in place of a chainstay bridge) to the frame at the lower end, and to the brakes up top.
C is secured (using that term loosely) with a tie to the rack, but otherwise bolted on.
The entire operation was hurriedly performed one night with a surfeit of impatience after a vexing session of wheelrub; as a result I cut it too short. The gap has been addressed, in spirit at least, with one of the extenders from the Crud kit.
This
bodgeguard in three part harmony provides adequate protection from wheelborne elements, is blessedly noise free, easy to clean, and stays in place. W____ f__ m_.
Somewhat later: mudguards off. They worked, but the bike never felt right with them on.
Aaaaand back on again, though the rack is no longer necessary scaffolding, and I changed the front fork to a mudguard-friendly version.
Funny how things can feel wrong, then right again, in an ever-shifting reassessment of priorities.