The correct option is
C Browns'
When a surname is preceded by 'the', it is usually pluralized. The subject here refers to a family's house. Hence the surname would be in the possessive case, i.e., followed by an apostrophe (').
(As the name is plural, it will be followed by an ' and not an 's).
Option C: 'Brown' is a surname and it's in the possessive case Brown's. The house belongs to the Browns hence the possessive case. So, option C is correct.
Option A: Bill's is a singular noun (Bill) in the possessive case. It should be plural as 'the' refers to plural names.
Option B: 'Friend' is not in the possessive case. It should express ownership of the 'house'.
Option D: Similarly, 'families' also does not express possession.
Hence options A, B and D are incorrect.