Who are those excused due to ignorance? Does this excuse include ignorance of matters of fiqh, aqidah, and tawheed? And what is the duty of scholars in this regard?

The claim of ignorance and being excused by it requires elaboration. For matters widely known among Muslims, such as what is necessarily known of the religion, creed, and the foundation of faith, the claim of ignorance is not accepted. Examples include ignorance of polytheism (shirk), the obligation of the pillars of Islam, or mocking the religion. These are matters that Allah and His Messenger have clarified, and it is incumbent upon scholars to propagate them to remove ignorance. As for issues that may be obscure to some, such as certain matters in transactions, prayer, or fasting, the ignorant person may be excused. However, a Muslim living among Muslims is not excused for being ignorant of clear prohibitions or for neglecting known obligations, unlike someone living far away from Muslims; the latter's case is with Allah and he will be tested on the Day of Judgment.