Proper nouns in plural form frequently use the article 'the'.
Options C and D: 'The' is a definite article that comes before specific nouns. The proper noun here 'Wilsons' refers to a specific family of the name Wilson. Hence the article 'the' is most appropriate and option C is correct.Usually, proper nouns in singular form do not use articles. Since the noun here 'Wilsons' is plural, option D is incorrect.
Options A and B:
'A' and 'an' are indefinite articles. They modify nouns that are non specific, or not known, to the reader: 'a lady', 'an apple'.
Since the given noun is specific, options A and B are wrong.