So I had a talk with Dad and told him to stop nagging and to be nice to her. He's frustrated cos she's still smoking and won't listen to him. I said we cannot stress her out as it causes anxiety hence more pain. It's weird that I'm lecturing my 70 yr old dad!
Later on, my mom told me she just wanted to scare my dad by telling him to stay at my place. She knew he wouldn't go and hoped he would be nicer. Good thinking, mom!