Realizing that he hadn't enough money and---to borrow from h

and连接的是realize和want这两个动作,所以二者应该用同种表达方式-ing,根据文中意思说是不想问爸爸借,前面加个not,就行了.
不选A的原因：句中的主语是he,前面的Realizing that he hadn't enough money and___to borrow from his father ,部分是伴随状态,主语同样是后面的he,所以省略了,如果用not wanted就表示被动,被不想,意思不符合,此处表主动,不想,所以应该与realize一样用ing形式.
不选B的原因：不能说no to want,没有这样的说法,你可以说don't want not want .