I had to do all this for my OH who had PD then fell and fractured his hip, resulting in a lot of what you are describing.
I guess I was a bit younger than your Mum when doing all this and it was an enormous stress in every possible way: physically - he always needed to open his bowels just as the carer had left; emotionally - watching my erudite husband degenerate mentally and physically was agony.
I could not move him at all even though he was not a heavy man - I have a back problem and it was just impossible. And he used to be paranoid at night and cry out in terror - so add in lack of sleep for your Mum.
It takes over your life completely - your home is not your own - people in and out all the time: OTs, physios, district nurses, doctors, ambulance people, social services etc. etc. It is a veritable blizzard of people and frankly it did my head in.
He needs to go to a rehab hospital at this stage for proper intensive rehab to get him to his best state. It really does not sound as though he is well enough to be at home.
If there are issues about funding his care when he goes home do feel free to pm me - there is very little that I do not know about this - knowledge gained through bitter experience.
If he is virtually bedbound then he is not at a stage where he can be properly and safely cared for at home.
And the incontinence is the straw that breaks the camel's back - urinary incontinence in a man can be dealt with with a Conveen catheter (like a condom that leads via pipework to a bag) but you finish up changing it, dealing with accidents etc. As for faecal incontinence, that is frankly a nightmare.
I am so sorry you are all going through this. My strongest advice would be not to agree to him coming home until further rehab has been undertaken, s home assessment been done, and a full and adequate care package been put in place.
My OH finished up in a nursing home for his last few months - I simply could not cope any more. I find it hard to even write this. It is massive drain on everyone's resources: financial, emotional, physical. Do not underestimate how hard this will be for your Mum - I put a brave face on it, as no doubt she will - however stressed she seems to you, multiply by 10 to get a more accurate picture.