In addition to the answer provided by Attorney Hunt, you mentioned that you may want to sell the house. If in fact the house was titled in your mother's name and you need to probate her estate, you will need to file a formal probate. The alternative is to file both an informal probate and a petition for a license to sell the real estate.
I might add that the procedure is not as straightforward as it was. You would be best to consult with an attorney in the county where your mother lived.
In closing I want to also say how sorry I am for your loss and I wish you the best.
I am sorry for your loss. What you need to file with the Probate Court depends in part on how the bank account and house were titled. If in your mother's sole name, then you would generally need to file a petition for probate and a bond form to begin the process. Under the new Massachusetts Probate Code you would have the option of filing a formal or informal probate. Which you file depends in part on whether your brother is willing to agree to your petition for appointment as executor. You may want to consider discussing these issues, as well as other issues concnering how to administer the will once it is allowed by the probate court, with an attorney.
I'm sorry for your loss
One other thing to add -- the Probate Courts are finding themselves overwhelmed by all the changes in the new law (which only went into effect on April 1) as well as by staffing cuts. If you try to ask them substantive questions, in all likelihood they'll tell you to go get an attorney. You'll need an attorney anyway to advise you about procedure, taxes, real estate issues, and so forth. So go find a good local probate lawyer and save yourself some stress.
E. Alexandra "Sasha" Golden is a Massachusetts lawyer. All answers are based on Massachusetts law. All answers are for educational purposes and no attorney-client relationship is formed by providing an answer to a question.
I am sorry for your loss.
I agree with the others, especially the sentiment of Attorney Golden, that the courts are so overwhelmed right now. If they answer the phone, they are unlikely to be able to help you, and they will expect you to do things correctly. Sometimes a mistake will lay dormant because they do not catch it, and then cause a problem months or years later when the parties need to sell the house, etc.
To generally answer your question, however, you will need to petition the court for your appointment as personal representative and have the will allowed. You will want to deal with the Probate and Family Court in the county where your mother resided at the time of her death. My advice would be to retain counsel.