Scary, frustrating, worrisome I have never had to deal with a dog with dementia, but have had two cats with what I call kitty Alzheimer's.
I believe there are some drugs you can try, sometimes they work, sometimes not. In the short term, can you let her out dragging a leash? Might make it easier to catch her, but you might still need your DH to carry her in. Unless the weather is bad, I'd just let her stay outside until she comes in on her own.
I believe there are others on GT that have dealt with this, hoping they will have better advice for you.