TV remote for elderly mother with bad arthritis?

You can get a big remote with huge buttons. There is also voice control. Although I find that many voice recognition systems don't work really well with the elderly. They aren't trained for it. Not the elderly, but the voice recog systems.

97yearoldmom, LOL, the "black ear of corn" remote is one of the best analogies I've ever heard. AC has some products found through the Senior Care Products link at the bottom of the page. I found this, maybe it would help:
https://www.agingcare.com/products/big-button-tv-remote-446882.htm

The cable company changed in my aunts area necessitating changes in how she could access her tv. The new remote looked like a black ear of corn it had so many buttons. My nephew found a small one with a volume button and a channel button and a LC (last channel) button.
You can slide a cover down and see numbers for the channels. He programmed it for the channels she watches so when she presses the channel button it goes from one to the next. It took a little while but she figured it out. I think he found it on amazon.
Shes 92 with vascular dementia. She can hear so don’t have a solution for that.

I Googled this and got 229,000 results.

The RNIB does a simple remote for people with visual impairment for £20 - I'm not suggesting you get that one, but it is a guideline for what's technologically possible and what you might be paying for it.

But. If your mother has dementia, I'm afraid all bets are off. Past a certain point it is not that the remote is difficult to use, it is that the brain is not making sense of anything much. In that case, I guess you could look into setting up some kind of home hub so that you can operate the tv for her?

Dad has headphones to wear when watching TV. That way he does not disturb the whole house when he increases the volume.

Someone bought my Mum a sound bar for her TV, but she does not like the sound of it, so she chooses to use the regular speakers and turn up the volume.

There are programmable remotes with fewer and larger buttons.

I might check with a website that offers devices for those with disabilities. Perhaps, something with voice control would help? There are also remotes with very large buttons, which might be easier to manipulate than those with the tiny buttons.