The 2 characters does stand for Guest Family.
History used this term but refered this group as out siders.
At one time this group like many up northern lived in a housing type enviroment known as a hutong.
Up in norhtern china there are tourist who have interest in this type of culture take hu tong tours.
No sure which dynasty there was a hu tong that for some reason offended the goverment.
This group ran and start to live and hide in the mountains and always moving their settlement.
This the hakka idea.