Husband and wife have joint property. If there is no clear agreement, both husband and wife have 50%, then the inheritance is 50% of the property, which is 1/2.
The average distribution of inheritance means that the mother, herself and sister each get the property of1/2 *1/3 =1/6. After the division, your mother still holds the property right of 1/2+ 1/6=2/3. According to Property Law No.95,
Conclusion: If your mother doesn't agree to dispose of the property by herself, she can't get the right to dispose of the property even if she goes to court. It is nothing more than judging that your mother will compensate her sisters for their due property in cash, 50W* 1/3≈ 17W. After paying off the money, the property was changed to your mother's own, and the relationship between mother and daughter broke down after the lawsuit. In the end, none of you got the property.
So I suggest you two leave the house alone and treat the old people well. The house is yours forever.