Caring for Disabled Parents?

My sister had a stroke about 8 years ago and is paralyzed on her right side and can't do any household chores cooking, cleaning, or laundry. Her husband had to have his leg amputated and probably will have to have the left leg amputated because of blood clots. They have 3 children including a daughter that has her mom's power of attorney. She refuses to go to her mom's house to help with anything. I have been there after she has come to visit and there will be dishes in the sink with maggots crawling in them. I can ask her, didn't you see the dirty dish and she will say, yeah but it's not my job. They both make too much money on their disability to get any type of help. Can their children be held responsible if anything happens to them without proper care?