Only when she received the invitation to a birthday party                  the old dress out of the wardrobe and tried it on, only                  it didn't fit.

she has taken; to be found

did she take; to find

she had taken; finding

had she taken; to find

考查倒装句和非谓语动词不定式。句意：直到收到生日派对的邀请，她才从衣橱里拿出那件旧衣服试穿，却发现不合身。“Only + when从句”位于句首，主句部分要使用部分倒装的语序，根据received可知，主语为一般过去时，则为 “did she take”；“only to do”的意思是“不料 (却)……，结果 (却)……”，表示一个没有料到的结果。故选B。