I need suggestions. Help

Even though you regard a facility or even home help as "out of the question" and "unaffordable," I suggest you start working with Medicaid right now as to how to accomplish this, for when and not if you need it.

Take a look at your floor plan of your house.
Is there a hallway leading to the bedrooms that include the bathroom, your bedroom, and Mom's bedroom?

Install a door there.

Lock it at night.

You could also install a row of lights leading from her room to yours, to be used as directional signals or reminders of where she might go. That is if you think
she could cognitively do this.

Both you and your Mom must have been scared to see police. Exiting the house through the garage is just what a thief/intruder might do.

Maybe get a consult from your security provider for future reference.

Thank you all for your suggestions.
she does have a bathroom in her bedroom. The gate might work. I’ll need to make sure she doesn’t have anything in her room she would be able to use as a way to climb over it.
You all are lifesavers when it comes to a sounding board!

You cannot lock her in her room. Its against fire code. I used a baby gate positioned high so Mom could not climb over it. She never tried to take it down. Try a dark throw rug in front of her door going out. They think its a hole and won't go over it. Combine it with a baby gate.

If Mom is never left alone, then you may want to put a key deadlock on the inside of the door. Yes, against fire code. My cousin did this because my Uncle kept trying to get out. He was never alone. As soon as he passed, my cousin took them out.

https://www.alzheimerslab.com/door-locks-for-dementia-patients/

This is what we installed. You can unlock it from either the inside or outside of door.

I use confounding locks on the doors to the outside (except to the back yard) and the basement. on the gates for the back yard, I have child security locks that she cannot figure out but any one who needs to get back there can open.

So, if she gets out, it just to the back yard.

Well, this is a big wake up call that tells you that current plan is no adequate to protect Mom. I am afraid when you say "Putting her in AL is out of the question" you rather have kind of closed the door on us. I honestly cannot imagine that placement will not be the ultimate the ultimate solution. Things are so unlikely to get better where the wandering is concerned. It will begin to happen during the day when Mom is not right at your side.
I agree that locking her into her bedroom would not be safe. That would be my worry with gates and locks as well. I just am paranoid about fires. And as I said I fear Mom may begin to wander farther during other times of the day. I think that Cashew's idea is a good one, about Mom being able to get no farther than the yard, but don't know weather conditions where you live, and if cold or too hot that could be far enough to cause damage, and certainly a lot of worry.
I wonder if you could simply CLOSE her bedroom door, and install some sort of trip alarm that goes off at your bedside when it is opened. That would be assuming she has her own bathroom for those frequent bathroom trips. You might speak with an alarm company and explain your exact situation.
Afraid that's the best I can come up with and surely do hope others have experience with this and good suggestions. Wishing you the best.

In reading Midkid's reply, I did remember baby doorknob covers. It has to be a round knob. The covers are plastic and fit over the knob. For Mom they just go around and around. Only you know how to use them correctly.

And the baby gate, mine came with an accessory that allows it to be used as a gate, installing it to the door frame.

Deadbolt and either unplug the garage door or find a way to disable it. We had to do both with my mother for a while. Inconvenient but necessary.

Deadbolt and either unplug the garage door or find a way to disable it. We had to do both with my mother for a while. Inconvenient but necessary.