1. IF brother's name is not in the Sale Agreement, THEN you can easily restrain /restrict /refuse him entry into YOUR house, since you can documentarily prove that money for house was financed by your resources. This is irrespective of the fact that it stands in joint name with mother. ANY dispute on this would have to be resolved via a Civil Suit for Declaration in the Civil Court, supported with all documentary evidences and witnesses.
2. However, IF Mother has executed a WILL document, giving property to brother, THEN said brother can contest the same in court for his rights. Here too he would not get success, IF you can documentarily prove that money for house was financed by your resources.