aging parents

What do I do with an elderly mother that is stubborn and selfish? Do I just let her go on as she has been going? Basically I have been ignoring the situation. Or do I put my foot down and make everyone mad. She has made bad financial decisions and now barely has enough money left to eat on. I could take over her finances and get her out of this hole but the cost to me would be arguing with her all of the time about how she needs to be careful with her money. The balance is allowing her to maintain her adult freedom but also having someone to watch over her decisions.