Your brother should take the case to a family law attorney. If the house was solely her her separate property, then she had very right to sell it without his knowledge. The community may have a claim in the mortgage paid and remodeling, etc. These will not change the character of the property.
If they bought the house in marriage, there are only three ways to hold the title: joint tenancy, community property, joint tenancy with right of survivorship. She cannot out herself on the title as an unmarried woman, without a quit claim deed from your brother.
The only way to figure out is to review the sales contracts.
