Oh, poor baby. This is what I'd do to start. Wash that hoof with warm soapy water, alternately soaking for several seconds and then scrubbing with a tooth brush and then soaking again, and then scrubbing... All the nooks and crannies.. Then you should be able to inspect everything much better.
Then I'd start snipping. If a bit of hoof wall has folded over, snip that away. If hoof wall has separated away, snip it off. If you see or feel a hole developing anywhere (check the hoof walls between the digits, I often get a hole in there and it is hard to see, but you should be able to feel one) Snip around it until it is level with the rest of the foot. If you feel a hole between the digits, then also snip the same place on the opposite digit to prevent pressure and rubbing.
Make the bottoms of the hoof as smooth and flat as possible to prevent rough areas picking up and holding mud. While the hoof is still clean, I'd scrub it again with a copper sulphate solution, or a zinc sulfate solution, and I'd let it dry before allowing her back onto dirt.
The next day, If you did not trim everything (hey, we can only do what we can do and sometimes that isn't everything that we must do, right?) I'd do it again. Keep cleaning, snipping , smoothing, and coating.
And I'd find a way to up her copper and zinc if I could. Keep her out of the mud if possible, but the scrubbing on of the copper or zinc and allowing it to dry clean, will help counteract the mud/muck she gets into.