Correct option is A
The hymns and poems of Sant Dadu Dayal (known as Banis, Dadu Anubhav Vani, or are part of the Panchvani anthology) were primarily preserved and compiled by his disciples. The two most significant compilers mentioned in your list are:
(iii) Rajab Das (or Rajjab): He is one of Dadu's chief disciples and is credited with compiling a substantial portion of Dadu's verses, specifically the Dadu Anubhav Vani (The Utterances of Dadu's Experience).
(iv) Sundar Das the younger: He was a highly learned and prolific disciple who also played a crucial role in collecting and preserving Dadu's teachings. His own body of work is a major part of the Dadu Panth's literature.
Although the other options listed were also Dadu's disciples, Rajab Das and Sundar Das are universally recognized as the central figures in the compilation of his works.