Coping techniques, Dad has dementia, failing health, Mom being irresponsible. Any advice?

My parents moved 2 years ago about 1mile from me so I can be of more help. Dad has dementia, can't drive and has failing health. Mom took him back to their former state of residence to visit other children, 4 times last year, retuned and was sick for months afterwards, and spent thousands of dollars taking my grown brothers and sisters out to eat. She finally made the decision not to travel because of dads health. I manage their money because she cannot (paying excessive late fees, she does not Remy to pay). Yesterday I got a text from my brother that he is driving down and picking mom & dad up and taking them to Indiana, mom had called and asked him to do so. She is going against her own decisions, doctors advice and family members recommendations not to travel or stay longer than a week. Not to mention the whole famy was driving 9 hours to see them over Thanksgiving and this brother has no problem accepting large amounts of money as "gift". I'm so frustrated, this is same pattern and they will return and I will need to cart them to three doctors appt a week for months.