Do I have to file a form 1041 for 2018 if my Mom's house did not sell in 2018? I was required to get an EIN for a contract that was later cancelled.

I'm sorry for your loss!

No - You do not have to file a 1041 return for your mother's estate, unless the estate has:

1. Gross income for the tax year of $600 or more, or

2. A beneficiary who is a nonresident alien.