Mother in law with lung cancer having severe panic attacks unsure of what to do

First time I've ever been on one of these sites my partner's mum has lung cancer she is stage 4. The tumor has filled one of her lungs, and was only a couple of days ago we found out it has spread to her bones and blood. She is now at home with constant oxygen and she is very week. She is only 63 and it is heartbreaking for me and her family to see her decline so much. She doesn't seem to be in much pain but currently she is sleeping most of the time but very concerned about her quality of life as she keeps having severe panic attacks which cripple her mentally and physically. Her legs and feet are extremely swollen and she keeps sleeping half on the floor and on the bed could anyone advise us on what to do to get her back to a better quality of life. She is on medication for the anxiety but doesn't seem to be helping at all. She's quite a stubborn lady so we're struggling to help her Also she doesn't know what stage her cancer is at as she didn't want to know all she knows is that the lung cancer has got slightly bigger