To get this achievement, you need to escape to Obristan during the last 3 days of the game (from day 29 to day 31) with all of your family.
Firstly, you need to get enough passports from Obrista (1 for each member still alive in the family & 25$ / member too).
Good to know : if some member of your family are dead, the escape will be easier to get (smaller amount of money & passport needed)
Once you have enough money & passport for each member, you can escape to Obristan after one the last days of the game (from 29th to 31st). This will end your session here & achievement will pop.