Aunts estate closed in December of 2017 as insolvent. received a 1099 form from one of the creditors for tax year 2018. Does a tax return need to be filed for this?

since the estate has been closed and is insolvent, I wouldn't file anything.   if you get a letter or notice from IRS respond at that time.       this assumes the id# on the 1099 was either your aunt's or her estate.