Parents made will, dad died, can’t afford to probate, son trying to get it all.

Although we do not know what the facts are in your situation, title to the family home (assuming a long-term marriage) is usually held by husband and wife as "joint tenants" with right of survivorship; that means when the first spouse dies the title passes immediately, by operation of law, to the surviving spouse.  If that's the case here, your mother would own the home and has the power to keep it, sell it, give it to a sibling, or give it to charity.  It would be hers, regardless of what a Will provided. (On the other hand, as you are in Texas, it might have been held as "community property" in which case it is conceivable your father could have attempted to transfer his interest in the property via the Will in some other way. In that case title will be clouded.)

sellLegal ownership of the property containing the house

If the deed to the house was in both your parents' names, especially if the deed speaks of them as husband and wife as is usually done, your father's will probably doesn't matter, because the house automatically became your mother's property, by herself, when he died.

What your brother is trying to do is just plain wrong, unless he is either paying full value for the house or making a written promise to take care of your mother's needs for life, which doesn't sound like what he has in mind.

I once worked on a case something like this in New Jersey, where one of three daughters got title to the house.  Even though she did it openly, and basically meant well, the court later threw out the deal and made her share the value of the house equally after the second parent died.  The lawyers ended up getting a lot of the money.