Oh, poor guy! So not only does the world suddenly not make sense, but he can’t even hear properly get auditory cues. I’m so sorry you’re all going through this. 
One thing my grandma was able to tell me was that it was hardest when she wasn’t confused, exactly, she was just wrong. She knew where her house should be, and what it should look like, and where the bread was kept, but all her knowledge was of a house she hadn’t lived in for 40 years. So while we were trying to correct her, she was absolutely certain she was right, because she was…she was just out of date.
That helped me to understand a little better what she was feeling. I mean, *I’ve *done that before - like been certain that I put the spare house key in the junk drawer when it turned out that’s where it lived in my last apartment, but now the spare house key is in my jewelry box. It *is *very frustrating. And that’s how every single thing in her life was going. I’d have a temper tantrum, too!
With her permission (when lucid) I simply began to tell her I’d just moved everything instead of correcting her, and I’d “find” it for her. It didn’t help her to be able to navigate her home, but it helped her to be “right,” and that was half her battle. I had to swallow my own pride around being right, but considering what her reality was like at that point, it was the least I could do.
My cousin hit on a phrase that really helped her, as well. When Grandma started getting upset because she knew her memory was failing, my cousin would say, “That’s okay, Grandma, you remembered a lot for a long time. Now it’s my job to remember for you.” Patronizing? Yeah. But for some reason it calmed her down.