What was the 'dharna' that the old Deshmukhin undertook in Shirdi, and why did she do it?

The 'dharna' undertaken by the old Deshmukhin was an intense fasting protest. The source material in Chapter 18 explains that she gave up all food and even sips of water for three days and nights. The reason for this extreme penance was her firm resolve to get a 'secret mantra' personally from Sai Baba. She believed that an instruction was only pure if it came from Sai's own mouth and was unwilling to go elsewhere or accept it from anyone else. Her dharna was a final, desperate act to be made a 'recipient of His grace' or else fast unto death.