Why did Sai Baba give eight rupees and eight annas to the bards and entertainers who performed for him?

The provided text from Chapter 29 makes no such connection. It mentions two separate events that your question combines. The chapter states that 'bards recited, entertainers performed' as part of the general crowds that came to Shirdi. Separately, it describes a specific group of four Ramdasi devotees, and it is to this group that 'Baba also gave them eight rupees and eight annas, as pleased their minds.' The text does not indicate that the bards and entertainers received this specific amount; the eight rupees and eight annas were given to the family of four Ramdasi devotees.