Do it for her so she has nothing left to do?!
Maybe she can make a list and you or your family can simply knock those items off until nothing is left but for her to rest.

Some people tend to hide their emotions by staying busy, it may more of a mental health situation than simply overworking herself. No time to think means you aren’t sad, if you know what I mean.

This may be the sweetest question I’ve ever answered.

Do stuff that you know needs to be done without her asking you to do so. Like emptying the garbage, run the sweeper, dust, empty the dishwasher if you have one, clean the bathroom.
This is a great question.

Look around. Do what needs to be done. And do it without asking her.

Nurture her by telling her to sit down every once in a while and bring her a cup of her favorite hot drink. Ask her to sit and watch something on tv with you.

I am very much like your mother. Telling me to relax and take time for myself does not work. Asking me to sit and hang out with you does not work. You know why? Because there’s stuff to do and it ain’t gonna do itself.

I’ll elaborate on what @LuckyGuy (and @chyna and @KNOWITALL) suggested: Look around. Do what needs to be done. And do it without asking her… regularly. Every day. Not just once or twice. And don’t half ass it. Do it right.

Then she can take it easy for a bit.

My wife, as I’m lugging clothes up and down two flights (multiple times a day) will say, “Can you ever relax?” — and yet she doesn’t do them but enjoys how clean clothes just magically appear in her closet.

Some people do a crap job of all the “stuff” that needs to be done, so often it’s one person (usually a mother, but not always) who ends up having to do everything, simply because other people can’t or won’t do things in a thoughtful, complete, or timely manner, or on a regular basis.

The way to help is to find out what needs to be done, how it should be reasonably expected to be done, and on what timetable it needs to be done, then let her choose what she will do, and what you will do, then do it. But if you forget, or don’t do it on time, or don’t do it up the the standard it needs to be done, then it just makes life harder for the person who ends up having to do all the work, and finish everyone else’s work, and fix the things that weren’t done properly in the first place.

Exactly what @Kardamom said.

Hire a house cleaner as a gift to her instead and take her outside for a walk, home cooked meal or just coffee in a pleasant area ( park etc)
Anxiety comes in many forms and this may be her way of dealing with isolation now.

Thanks for all the answers, I will try my best to do them and take them into consideration. The thing is that my mom also won’t let anyone else do the work because she said she’d feel less of a mother. Also, I have a hard time doing things on my own, ACKKKK
ACTUALLY I GTG. I HAVE A MEETING TO GO TO. YIKES I ALMOST FORGOT