Dad never signed up for VA and needs help.

I don't believe you qualify for VA benefits if you never saw active duty. My dad was in the Marines and was not active duty so no VA benefits were available to him and even if they were he probably wouldn't have bothered since the VA is such a crap shoot as to the care they give our veterans. Most VA's suck.

The final discharge papers are the DD-214, which are supposed to be kept, so like others have said, check wherever he keeps things like his birth certificate.

https://www.va.gov/health-care/eligibility/ ;has the current eligibility info. Scroll down in that page to the “What if I need help filling out my application?“ section to find several ways to get help. 

I had to check on my dad’s eligibility for my mom. Making it through the phone line was a nightmare, but every time I got a real human, they were helpful. I got connected to our regional VA office, and they were fabulous. Also the VA has made a lot of effort in recent years to improve access to services so hopefully you’ll get an answer efficiently.

Dad must have a place he put his important papers like his birth certificate. My Dad had his in the same envelope they gave him at discharge. Unless your Dad was in the service during the Korean War or VietNam War, he is not entitled to Aids and Attendance. If your Dad ends up on Medicaid to pay for his care, he is not entitled to A and A.

Your Dad maybe entitled to go to a VA hospital for his doctors. He may be entitled to be placed in VA Nursing Home. You need to find his discharge papers. In my Dads there was a letter saying he had a right to VA benefits. You should have a VA dept in your county. Make an appt to see the VA rep.

Why not skip the VA filing and go straight to Medicaid when it is time. A and A will not be enough to cover private nursing care. Hospice will cover nearly 100% of care.

https://www.usa.gov/military-records Will be your starting place for getting all military records. A way will exist online to reach out to the VA for descriptions of services and how to apply, as well. Especially if your Dad was at Le Jeune where there is known to have been cancer contaminants and programs for help, it is important to access all the info you can online and start making calls and reaching out for help. So sorry for this dire diagnosis but do know that bladder cancer is treatable.

Call the VA - you could get a rep that is helpful.
Or call the Camp Lajeune number that has been on the news - if you have his dog tags that will have his number on it.
Look for his papers - my daddy kept them in a fire proof envelope in a file cabinet.
blessings to you.