准确的句子该是 The father wants his daughter 【to be taught 】the piano.
也就是 The father wants his daughter 【to learn】the piano.
若是动词want的用法清晰了,此题就好理解了 简单说几句吧：
1.want + 名词/代词 表达“想要什么东西”
His daughter wants a piano.他女儿想要个钢琴
2.want to + 动词原形 表达“想要做什么事儿”
His daughter wants to play the piano.他女儿想要弹钢琴.
3.want sb to do sth 表达“想让某人做某事”
He wants his daughter to learn the piano.他想让女儿学钢琴.
这种类型还可以做个变换 即：want sb to be done 表达 “想让某人被.”
题中的句子就可以做例子：The father wants his daughter 【to be taught 】the piano.
这个爹想让他家的丫头“被别人教点钢琴”----把这意思捋直了就还是“让小丫头学钢琴”.
4.want sth doing 表达“想被.” 此时,want的主语通常是“物” 如：
My hair wants cutting.我该理发了.-------- 即 我的头发念叨着“被剪”了
His watch wanted reparing.他的表该修了----------- 即 他的表嘀咕着“被修”了