My mom who is 83 might be coming to live with me. Since being in a rehab facility, she’s been wetting the bed almost every night. Advice?

If your mom has funds for care then you should rethink your decision to be her carer. It’s a monumental uphill task and needs just become greater. Better to have her live in a caring facility and you keep your sanity than have to move her later when needs are too great and you are burnt out.

If she is definitely coming to live with you, do this-
Remove carpet from her room and replace with LVP.
NO THROW RUGS
Get her a lift chair that is vinyl upholstered.
Hospital bed and bedside commode.
Hoyer lift
Use a waterproof mattress cover, then a chuck pad and then fitted sheet on top of that. Buy plenty of sheets.
She needs to be wearing adult diapers.
I'd have her spending most of her time in her room if she is peeing everywhere or else your house and furniture are going to end up smelling like urine.
Prevent, not mitigate

Nlight diapers. Bed size pee pads. Throwaways or buy reusable you can wash. Mattress pad with plastic built in underneath.

PS...Since this seems to have started in rehab, maybe it is stress from the environment? Drug reaction? Maybe it will ease up once she's out of there?

Call HDIS for home delivered incontinence supplies; I bet they will have some answers. Is it too late for you to say "no" to her coming?
Is she willing/wearing protective undies? If not then you'll want to protect your furniture as well. For that check out Crypton fabric but make sure it has the moisture barrier. Often sold at Jo Ann. Used in hospitals/hotels because the surface is washable and it won't go through to padding. You can have slipcovers made.
My mother's sheets were stained, not with urine, and I washed that and some clothing with persil and no scrubbing and it came out clean!
Sometimes you might have to just trash something. Also, I think it was the Vermont General Store, that carried a half slip that had a moisture barrier so no leaks...and I'm sure others will tell you about the bedpads that are washable and some disposable...you just want to do layers so that you don't have to rip a whole bed apart every time...

You can purchase waterproof pads for the bed. I would buy a waterproof mattress pad, then medical companies supply waterproof incontinence pads that are small and easy to wash. They sell them on amazon. In addition, absorbent diapers for bedtime provides additional protection.

Vinegar and double rinse

Odoban works really well to get urine and fecal smells out. You can spray it on before washing or add it to the laundry machine like you would do with bleach.

Alternatively, you could go to a pet store and buy something used to clean up after dogs and cats. The enzymes work for human accidents, too.

I second Lealonnie’s idea of the mattress cover and lots of disposable pads/chucks to put everywhere she sits or lays. Good luck.

Uh, I'd rethink the entire 'living with you' situation right away. Or get used to the house reeking of urine along with the carpets and everything else she comes in contact with. Is it absolutely imperative that she live with you? What about Assisted Living??

Anyway, for the urine soaked garments, use a vinegar wash:

Mix one cup white vinegar to three cups water (1:3). Coat the urine-stained item with this solution and allow to sit for a few minutes.
Cover the stained area with baking soda, if you wish. ...
Wash the urine stained items in a washing machine set on cold or lukewarm water. ...
Air-dry the urine-stained items.

For the bed, purchase a plastic mattress cover and Medline Extrasorb chuck pads on Amazon.

https://www.amazon.com/Medline-Extrasorbs-Drypad-Underpads-Permeable/dp/B07GYZNDY8/ref=sr_1_1_sspa?crid=60PNIEXGYCJ6&keywords=medline+extrasorbs+ap+30x36&qid=1582245028&sprefix=xtrasorbs%2Caps%2C1615&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzVTdVSlhHQU1NUUlIJmVuY3J5cHRlZElkPUEwNzc1OTI4MVM1WTNSSlU1V0xHMiZlbmNyeXB0ZWRBZElkPUEwNDY3MTgzMlhNU0lXQUI0RFdRNyZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

She will need to wear Depends to go to sleep and you can also buy doubler pads to insert into the brief to soak up extra urine.

Good luck