I'm sorry for your loss.
Did your mother live in the home until she passed? If so, you may have a case for an implied life estate. In that event, your basis would be the fair market value on the date of your mother's passing.
See https://www.law.cornell.edu/cfr/text/26/20.2036-1
You might want to provide details on the circumstances of the transfer from your mother to you, but you should absolutely seek advice from local legal or tax counsel.
