How can I help my dad who has been soiling himself or not making it to the bathroom on time and creating a mess in the hallway?

Yes, it looks like you've been dealing with this issue for quite some time. I would consider that your father is not mentally capable to comply with what you are expecting of him or that he has become incontinent and is unable to physically comply. So, I'd explore tending to his Depends, changing, cleaning, etc. I'd ensure that he is always supervised, so that he's not trying to do it himself and getting it all over the place. You can try getting him on a schedule where he's placed on the toilet at scheduled time to see if he can use it.

One member solved the problem by making parent clean up their own mess. Took 3 days but they stopped.

Cut out coffee and juices. Apple especially. Bananas and cheese bind just don't overdo.

Sounds like Dad is still refusing to wear Depends, right? You said last year that you were about to take away his briefs so he’d have to wear them. Did you? I don’t remember. Does Dad have dementia? Does he understand he’s not making it to the bathroom and making a mess in the hall?

Two things to consider. Pay attention to Dad’s diet. Spicy foods, fatty and/or fried foods, too much fiber, too much water or juice can all cause an urgent need to “go” and contribute to failure to get to the toilet in time. If Dad has mobility problems, that adds to it. Second, invest in a commode chair for Dad’s room if that’s where he spends most of his time. INSIST he uses it. Try to determine if he has these accidents at the same time and suggest he goes and has a sit down. If it continues, speak with his doctor. It may be IBS or something else in his gut.