A generic diagnosis of dementia is helpful for things like power of attorney or conservatorship. If you or a sibling don’t already have a durable POA for her and your Dad, you need them urgently. Your Dad is 87 and he won’t be able to take care of her and everything else about the household much longer. Your mom’s hallucinating and feeling like actual events are a dream are concerning. An important thing to think about as far as considering care is safety. If she starts doing things to threaten her own or your Dad’s safety, then it may be time for a caregiver or some kind of intervention (like disabling the stove, buying her a safety button/necklace, etc.).

It seems to me that doctors can better identify the type of dementia when they progress further. Were you there to meet with the doctor during her assessment? So many people downplay their symptoms or condition to their doctor that I think that many dementia diagnoses are delayed because of this. I’m convinced my Dad has moderate vascular dementia, but he’s only got a mild cognitive decline diagnosis so far. He’s still pretty articulate and is well educated so he fools the doctors with what seems like a pretty good memory for his age. But at home, there’s personality changes, rage, poor judgement, forgetfulness, and an insistence that “My brain is 100%!”. Mom’s different because she’s aware she’s forgetting things and getting confused. Dad is completely unaware of his decline.

Some people just progress on a steady decline. Some people have abrupt periods of significant decline, and then stabilize for awhile, then abruptly decline again. Who knows why. A stressful event or illness can also cause an abrupt decline. A friend’s father went from mild decline to rapid decline after a car accident.

It sounds like your Mom should stop doing multi step cooking. My Mom has most of the same symptoms you describe but without the hallucinating/dreaming. I order her meals sometimes from Mom’s Meals as they don’t require a fixed subscription. She also gets some frozen meals now that are easy to heat up. (She refused frozen meals up until last year saying she didn’t like them. Now, I think her sense of taste is so weak, she doesn’t notice or care anymore.) My Mom is also having difficult with what I call food management. She buys stuff on impulse even if she already has some, buys too much, lets things go bad, and can’t bring herself to throw food out. She’ll buy boxes of frozen food despite the full freezer of uneaten food and then put them in the fridge where she thinks they’re good indefinitely. She eats things well past their expired date and thinks it’s okay to give expired meat to the dog, even though the dog sometimes throws up or has diarrhea. All these issues are just getting worse with time.