Sorry about the loss of your mother.
Generally speaking, if your mother was the sole owner of the home when she died and either (1) she left a Will appointing your sister as executor of her estate or (2) your sister has been court-appointed to serve as executor, then your sister would have the authority to sell the house.
But her authority would be limited to selling the house for your mother's estate and the proceeds would need to be distributed according to the terms of your mother's Will (or state intestacy law if your mother left no Will).
Undoubtedly there's detail and context to this situation not mentioned in your question. So if you have any doubts about your sister's actions, I'd encourage you to contact an attorney who specializes in estate matters for formal advice on the situation. Hope that helps.
Hi Joseph! I can relate to your loss - my father just passed away in Feb of this year and the four of us are working through his estate. We are in a similar situation. My sister is the executor and has the right to sell the house in order to settle the estate. One of my siblings is not in total agreement on the selling price, but at the end of the day, she gets to make the decision.
I encourage you to listen to your sister's side of the story. Keeping the house means continuing to pay any mortgage, utilities, insurance and maintenance fees. Spending this money reduces the amount available to distribute to everyone. Also, it is time consuming and mentally exhausting for one sibling who is responsible for getting this work done. Settling a parent estate is an underappreciated job.
Larry's comments are spot on. If you feel the exectuor is not performing his/her duties appropriately, contact an attorney to help sort things out.