The Texas Constitution and estates code provide that even if the children take ownership of the home that they cannot take the homestead occupancy rights from her.
This right to stay is not absolute. She can abandon it or be compelled to move if she allows the property to be wasted. They must pay for insurance, taxes (at least some), upkeep.
Act quickly because there are circumstances where the stepparent can even pass that homestead right on to their new family.
Call if you have any questions from a similar situation.
See the Texas Constitution & Texas Estates Code Sec. 102.005. PROHIBITIONS ON PARTITION OF HOMESTEAD.