I'm going to try to answer this more from the purpose of this site. Financial advise more than family advise, but some of that too.
First off, do what you feel you need to. I would take care of my mom too, but I am also 40 years old. When I first started working I had no idea how many times I would be tightly budgeted, plain out of work, or having multiple jobs because one wan't enough. You're young. You WILL lose your job or choose to go to another some day. If not that, then other needs like housing, transportation, medical things, etc could also make your income less stable. If she develops a dependency on an assured cash flow from you it could send her to the streets the one month you can't help out. Obviously neither of you want that.
So here's what I would do. I developed a few passive revenue streams for myself over the past 10 years or so. Anyone and everyone can and should do this for themselves and impart the information upon anyone they care about. Not do it for them, mind you, but explain how they can do it themselves and even help get them started if they aren't confident they can.
Personally, I make things and sell them online. Things I do when watching TV or in my down time. For the sake of this discussion, let's just call them arts and crafts although it can be technical things, buying and selling actual tangible products or making coloring pages to sell in digital packs on etsy... yes, that's a real thing.
The digital items are best because you make them once and they just keep trickling cash into your account and you do nothing. Those are harder to set up, but they are plentiful and all it takes is a little poking around ebay and etsy to get an idea. I have about 30 of them, all my own designs, and I make $10 - $20 a month from just those alone.
I also make pillows. They take about 15 minutes to sew, cost about $5 to make and sell for about $30. I make a ton of other things as well and they generate between $800 - $1200 a month give or take. I spend maybe an hour a day making, packing and shipping things. That is not too much to ask from anyone for that kind of financial support.
I bet your mom could use that kind of cash flow, and I bet you don't want it to be coming from you.
Ok great, so how do you tell someone all they need to do is make stuff and sell it online? If it were that easy everyone would be doing it. Thing is - everyone is doing it. That's why sites like ebay, etsy, and to some degree amazon exist and are thriving. Because the people to people marketplace is huge and there is a market for almost everything you can think of.
I got started by buying a $200 sticker machine. I drew some silly stickers. They started selling. I spent the income on newer and better equipment to make other things. Those things made money too and eventually built up to what I make now, which I am comfortable with and don't really want to get any deeper. It took me about 6 months to build up a unique store front that made about $300 a month and ever since then I just keep on experimenting with other "arts and crafts" just to diversify so I don't exhaust one particular category of goods.
I sell on amazon, ebay, etsy, and my own sites that I build on my own. The first 3 anyone can set up with minimal effort and begin selling today. I strongly suggest you set that up with her even if she has nothing to sell yet. Just getting started is the biggest hurdle for a lot of people. They think it will be too hard, or they dont like computers or whatever. Do not let her use this excuse. It is so easy anyone can do it.
Now about her. Everyone has hobbies, interests, or things they like to collect themselves. I started by asking myself "what do I want and why can't I provide that for others." My first products were jokes. Poo shaped pillows, stickers with semi-offensive statements conventional companies dont want to risk saying. Or just snarky coloring pages. They all sold and some sell very well. Your mom has something, be it a talent or an interest, she can supply for the world with very little effort. It's between you and her to figure out what those are. Start by exploring ebay and etsy to see if others are selling them and if you can compete.
From there, consider a little quality time by making them with her and seeing about getting her moving on her own. You may have to explain the volatility of your income stream and that she cannot rely on it in the long run, but for now, you can help her set all this up and see about filling in the difference between sold items and what you provide. The intention would be to replace what you provide with a good store front on a few sites and surpass that to the point of self reliance.
I also advise to put aside any difference you would have given her and roll them into safe investments like CDs or some other simple maturing compounding interest bank option. There are many. If you have already resided to the notion of helping her out, then you know what you can afford to spin into an investment. If nothing else, should you or her ever hit a critical point, you at least have something you can fall back on.
My brother got me into this. I got some family and friends into it. All of us say it is life changing and all of us make some kind of passive income just coming up with our own ideas and putting them out there. We can't all be anomalies. This will work for your mom too if she is willing to put the effort in. Do it with her and she will be all the more likely to succeed and alleviate you from what could be a very difficult long term financial commitment.