I need to help my mom

My mom has end stage liver cancer. Her biggest worry is my dad. She cannot rest peacefully until we figure out what is going on with him. She thinks he might have beginning alz. so I thought I might ask you guys. He says nothing is wrong and wont go to the doctor. I live in another state so I dont see the symptoms my mom and sisters see on a regular basis.
He is 61 years old and his main problem is memory related. He doesn't remember what people tell him from day to day. For ex. my mom has a lot of hip pain from her cancer and it hurts her much less if she can get up herself. She has told my dad over and over to not help her because it makes it hurt more. He does it every day. When they drive somewhere he forgets the order of errands they were doing...Walmat, Sams club and the grocery store. He turns to go to the grocery store when they were close to their 2nd stop at Sams club. There were other things but I cant remember them all over the past two years this has been happening (yes I see the irony lol)
He has also had a few issues of raging incidents over the past 2 years. He gets really mad at something and yells and paces around the house. My mom can calm him down eventually. Yesterday he threw a chair out of the bathroom into their bedroom hard enough to bend the metal chair. This is so very unlike my dad!
So what are your thoughts?

Thank you Kate. He doesnt drink but I never even thought about that. My mom feels safe so no problem there. Is there a difference between dementia and Alzheimers?

He is on medications. I will tell my mom to mention that if she can get him to go to the doctor. Thanks for your reply and concern

Social services can assist. They even can get a home nurse or doctor to observe