Help with making a house addition?

Currently my parents are living in a rental home and have been for 20 years. My father is 75 years old and my mom 72. My mom has diabetes and a heart condition which limits her mobility. My dad does most of the work at home and due to their low income status he works part time at a grocery store to make enough to put food on the table. As time goes on, my father will no longer be able to work and they will not be able to afford to live in the home they are in. Both my parents are adamant about not living in an Assisted living facility. I wonder if there is a state program that would help to subsidize adding an addition to our home that would give them a safe and loving environment to live in.