Hard times

I'm going through a very difficult time in my life. Some days it is unbearable to deal with my parents.  My father recently had a stroke and my Mom has gone down hill since.  Her memory is horrible. She recently closed a bank account and that "wasn't her fault".  She nor Dad will give any of their children a poa so we are trying to help them with our hands tied behind our backs.  Two days ago my Dad said something about not trusting my sister... whom he has named as executor of his will!  It's crazy!!  They are paranoid and forgetful... a bad combination. Mom called today to ask me about ordering Dad's medicine.  I've already done this but I hear her on the phone with the company trying to work it out.  Then when I say something about already doing it, I sound frustrated so she goes into this whole drama about how I don't understand what she's going through, etc.  She has no idea what I've been through either!  She can't remember it!  I know they are suffering.  Every social worker in this state would be on their side (I learned this from the nursing facility dad was in).  I understand they are going through the worse time of their lives, but they need help and refuse it.  As their child, what am I supposed to do?  They have refused to live with any of us, they are not keeping their house clean and they have a huge yard that needs to be taken care of. 
They took out insurance years ago that would help them through this time in their lives, yet they refuse to accept that its time to use it.  When I explained to my mom (every day for the past two weeks) that she needed my sister to help her with her finances (and that the doctor recommended it) she says Dad won't let her and he says he's going to take over them.  Dad can't add two numbers on a calculator right now, much less balance a  checkbook or write a check.  This is all crazy!  I know God is with me, but some days I just wonder how much longer can I endure watching them suffer at their own choosing.  Please God, give them a miracle!