What to do if my mom died and didn't leave any paperwork?
Question Details: Do we, her children, need a lawyer to transfer the deed? Do we need to become executor over her estate?
You should consult a probate lawyer in your area as you will need a lawyer to sort this out. Michigan may have some estate laws making it easy to transfer a deed if the home is your mother's only asset. However, if she had other assets and/or creditors, those matters will also need to be resolved. You definitely need legal advice.
Most states have simplified procedure for transferring a title to the home if the home is the only asset in the estate of a deceased. You should consult with a probate attorney in your area in this regard.
If your state does not have such simplified procedure, or your mother had other assets, creditors, then those issues will have to be resolved through probate procedure. To begin the probate procedure, you will need to file a petition for probate with the probate court in the county of your mother's domicile and petition the court for probate of the assets without the will. I would strongly suggest to obtain legal advice from a probate attorney in your area.