The correct option is C were
Here, 'were' is correct in Simple Past Tense because it
indicates an action that has already been completed.
'Was' is incorrect because the subject is in plural (a pair of pyjamasand a pair of jeans). Thus, with plural subject, plural verb (were) is correct.
'Is/are' is incorrect because the passage is in past tense, as indicated by the first line 'had been lying...for about three days'.