Safety Concerns

My parents are getting older, they are in their late 70's. My brother and I are becoming increasingly concerned about their safety around the house. My father is having difficulty walking due to knee problems. He and my mother are being very adamant about staying in their home so we are planning to do some upgrades. First on my list is installing hand rails for bathroom safety. After than I want to put in a ramp in the back. The stairs are very tricky there. Hopefully this will help them stay put longer.