We may never see that family again, but God brought them into our life for a purpose. God has reminded me time and time again that we really don't need to serve the Lord in a foreign county (He can bring a people from another country right to your door!), unless He truly leads you to do so, because we really have huge a mission field in the United States. I read the other day that the largest Arabic speaking church is on the outskirts of Washington, DC. We have probably about every single religion in our country and many people who speak foreign languages.
Pray and seek the Lord for direction on where He would have you to serve Him in this world. Time is short and there are so many people that have not heard about the Lord.