How do I handle my MIL who refuses to wear her hearing aids?

I have posted many times on this forum about my 90-year old French mother-in-law with dementia who moved in with my husband and me three years ago. I am feeling very exasperated by her increasing unwillingness to wear her hearing aids. Without them, she hears nothing... and I mean NOTHING, I can pound on her door or yell at the top of my lungs and she will not respond.

I am home with her during the day and am looking for employment. She often comes to me in a panic about an upcoming doctor's appointment or to inform me that our house cleaners have stolen something of hers. But she more often than not does not have her hearing aids in. I understand that she may just forget, but it is so chronic at this point. And it is draining me of any energy I have left after her overall constant complaints and demanding behavior.

The only thing that I can think of doing is to point to her ears to go get her hearing aids. Sometimes she just will push her ear right next my face for me to yell in her ear. I refuse. I have a 24-7 chronic headache condition from a concussion and screaming exacerbates my headaches.

I know that it is at least in part forgetfulness, but she somehow manages to make her way into our backyard 8-10 times a day for a smoke. She never forgets to take time for a cigarette. With the exception of when I prepare her lunch or when we all sit down to dinner, she more often than not is not wearing them. When I leave the house and need to tell her something, there is no way to communicate!!!

My husband is exasperated too.

Is there some possible way to get her to wear her hearing aids without these all too frequent occurrences throughout the day? How do I handle the situation when she is not wearing them? My husband says that I shouldn't even acknowledge her or try to talk/communicate as I have been mostly doing. Having any conversation is futile and I just get more and more frustrated. There are days that I feel that I am literally going insane.

Thanks SO MUCH for your advice, everyone!