1) if minor was one of the legal heirs and property has been sold without obtaining consent of court for minor share in property then on attaining majority within period of 3 year he can challenge the sale deed
2) it all depends who would be legal heirs of the husband on his demise . if he is survived by his mother , wife and children then wife cannot unilaterally sell the property . for minor share she would need court consent . for mother share her consent would be necessary