How do I get an elderly parent to use soap after toileting, etc?

I had this with my dad. He did some things but refused to shower and change clothes. I made the kitchen off limits, he wasn't able to go into my room so I didn't worry about that but I used gloves to touch things that he touched frequently like the tv remote or dishes. I didn't throw this in his face but I had to have some control. Mom had had c-diff at one time and I was trying to keep everyone else from getting it. By the way hand gel doesn't kill c-diff. You may not need this info but just throwing it out. I felt that he was still carrying it so I had to limit contact as they would do in the hospital. You just have to work around him. If he refuses to wash and if you're forced to use the same bathroom then you may need to clean (with 10% bleach solution if c-diff is a concern) every time he comes out. I hope this helps. I understand the stress of this situation.
What else does he lie about?

He acts friendly to me, then plays games behind closed doors to keep favor with some siblings who have a history of lies, thefts, conspiracy to commit fraud (Medicaid), etc. He acts sincere, but isn't when his agenda(s) conflict with the proven truth. My mother used to accuse him of lying, and I saw much of it as her bipolar anger. She wasn't ALWAYS wrong, but enough to doubt her credibility.

Dad doesn't want certain truths to be exposed, and protects the offenders. I think it's because they are the youngest. He wants family peace, but won't take healthy family leadership role.

I like your idea of making the kitchen off limits to reduce his area of influence. Even after I spoke with him about knowing he doesn't use soap except in occasional shower, he handled the collection of nearby silverware so they all have to be rewashed.

Thanks for your advice, and the c-diff info.

The part about the silverware made me cringe, sorry. My heart goes out to you.
As far as the lies. Does he participate in the activity of your siblings or just keep their secrets? Does he do anything that puts you or your family in jeopardy? If so you need to protect yourself there too.

When he talks with them, he shows support to them. He's two-faced, yet he wants family peace. I try to explain to him that his refusal to deal with problems has actually led to these situations. He talks about people behind their backs, but acts like a pal, not a father.

Yesterday I made some signs to caution people about his refusal to wash his hands, and left one at the kitchen table. This morning there was a tiny peace of soap on his stack of washcloths, as if he actually used it since his hands are so stiff he can't close them to hold something that small to suds up the cloth.

I'm interested to see what he's wearing today since he didn't even take a weekly shower last night from what I see. "Dear Lord, give me patience, and I need it NOW." :-D

Would Father use disposable wipes to clean his hands? Easier than soap and water, if ease is an issue.

You are not sure whether he took a shower yesterday? I'm impressed that a 95 year old man can shower on his own. Many people that age would need supervision. My mother (92) has stopped showering, but she does "sponge baths." Disposal washclothes are useful.

If your dad is 95 then I'm guessing your siblings are not in their 20s or 30s. Is that right? Maybe it is OK for him to act like a pal -- they really don't need him to play the father role, do they? (Lord help me if my kids still expect/need me to be parental toward them when I'm 95!) My siblings and I are more and more taking over the parent role to our mother.

Unless your father's behavior with your siblings is somehow harming you, I think I'd just step back from that and not try to supervise or fix it. You have your hands full just keeping him clean!