#1. 가족들은 요즘 잘 지내? - addressed to friends or younger people
#2. 가족들은 요즘 잘 지내나요? - addressed to younger people in a formal situation or the elderly
#3. 가족들은 요즘 잘 지냅니까? - addressed in a very formal situation
As I assume you are an ESL teacher in Canada, #2 seems a preferable option.