UndeRGround, Older folks almost always want to stay, very rare to bug out. I have seen that many times in my time, reasons were many, but they are always more “attached” to the property and way of living, it is hard for them to change everything and “go to uncertainty, when everything will be OK”.
Good suggestion is to convince them that they need to leave because they need to help you, or other family members, that they need to be with you. They need to have some sense in whole situation.
You are at the right place if you want to learn something new, lot of ideas are on forums here, I am learning too. Just ask.
Personally I would not like to be in suburban areas when SHTF, but nobody knows for sure, and it is definitely depends from SHTF scenario.