What to do when your parents with dementia are hazardous to themselves?

My mother is about 3 yrs into dementia. My father 5 yrs with dementia and CHF. My mother is the problem. As I have had discussions on here regarding her driving issues, we are still fighting with her on this subject. The major problem now is she just really doesn't think anything is wrong with her and she is going on with her life like she is fine with no problems. She is creating problems everyday. She picks up the phone and calls anyone to help her for every little thing. Everyday, all day long she looks for things wrong with her house and she is totally consumed with the problem until she has everyone crazy. She has 3 kids running in circles trying to keep up with her She is never satisfied. We take care of one problem and there is always more to follow..We are taking turns staying with them. Trying to intercept phone calls. Watching out for them. Recently they have had an oven fire, a fire on the stove, burnt food in the microwave. She will not stop. She is either planning meals and wanting to bake things, wanting to start sewing projects, wanting to fix up the house. We try to let her start some projects, but she can't follow through with anything. Before she gets one project done she moves on to another. She has project piles scattered all over the house. She is very sneaky about things, usually waiting until we are out of the room, or she gets up early to make her phone calls. She does whatever she wants. When SHE wants to do it. Her and my dad have a lot of doctors appts. We take them to all appts. We take her to the store more than we should. She is the only 88yr old that I know that wants to go to the store everyday. This is another problem. My dad is on a NO SALTdiet becausr of his CHF. She has an upright freezer in the garage that is full of bacon, ham, hot dogs, bologna, all foods he should not have. She says, "just because he can't have it doesn't mean I can't have it". But she doesn't fix anything else for him. I know I'm rambling, jumping from one subject to another, but this is how crazy she is driving all of us. I stay 4-5 days a week with them. Have practically given up my life. I had to cancel one of her many appts. to go to the dentist I have put off for the last year, she was not happy, called her brother to take her. By the way, her dermatologist said she has a spot of excema on her foot!! That was the appt. She got all upset about and had to call for a back up driver. She made up her mind she was going to go .... and she did. Whatever she wants....
So after babbling out of control, my question is. What do you do when your 88 yr old parents, who no longer can handle their financies, medications, making appts., now fires on the stove and in the oven, and by the way, the oven fire was due to a plastic vegetable brush she put in the oven to dry, and the crock pot was on the stove top and she turned on the stove. We were all outside when the plastic melted and caught on fire. And they do not want anyone there to help them. Do we honor their wishes? How do we go about getting help about this?
Thank you for letting me blow off a little steam.