What is the meaning of the term 'Maktubat'?

The correct answer is Option (4) → Written collections of letters.

Option (1) Conversation of sufi saints. — Incorrect. The conversations of sufi saints are called malfuzat (literally, “uttered”); the Fawa’id-al-Fu’ad, the conversations of Shaikh Nizamuddin Auliya, is an early example.

Option (2) Collection of paintings. — Incorrect. The sufi sources produced in and around the khanqahs are written texts; paintings are not one of them.

Option (3) Biographical accounts of saints. — Incorrect. Biographical accounts of saints are called tazkiras.

Option (4) Written collections of letters. — Correct. Maktubat (literally, “written”) are collections of letters written by sufi masters to their disciples and associates; they reflect both the shaikh’s religious experience and the life conditions of the people who received them.