If the house is in joint names, there are 2 ways your parents could be holding the property- as Joint tenants, which means the property passes automatically to your Mother, or if they hold it as Tenants in common, this means your Father's share passes in accordance with his Will, or if no Will is found, to his next of kin under the Rules of Intestacy.
Likewise, if the property is in your Father's sole name, it now passes in accordance with his Will or under the Rules of Intestacy if there is no Will.
On the basis that there is no Will, whether the property be held by your parents as Tenants in common, or it is in your Father's sole name, the Rules of Intestacy means your Mother inherits the property.
Therefore, your Mother is entitled to sell it, and am guessing that your brother has or will be applying to be her Attorney, to enable him to deal with the Sale.
As and when the property is sold, your Mother is entitled to the proceeds, and you and your siblings won't legally be entitled to any of the proceeds, on the basis there is no Will.
I hope this assists and answers your question.