24. why doesn’t berniece play the piano?  

She doesnt play it because she thinks its haunted because her mom said that when she played it, she could hear the voice of her dead husband

This is the answer I was able to find, 

     Berniece refuses to sell the piano, because it represents the family's past. Boy Willie thinks the piano is valuable only because it can be sold to secure his future. Doaker Charles, their uncle, acts as mediator between the siblings.