You need to file a Trust return. https://turbotax.intuit.com/small-business-taxes/

The return will generate Form K-1. https://www.irs.gov/forms-pubs/about-form-1041

The fiduciary of a domestic decedent's estate, trust, or bankruptcy estate files Form 1041 to report:

• The income, deductions, gains, losses, etc. of the estate or trust.
• The income that is either accumulated or held for future distribution or distributed currently to the beneficiaries.
• Any income tax liability of the estate or trust.
• Employment taxes on wages paid to household employees.

Whose accountant?  The Trust accountant or your personal accountant?  The accountant should prepare the 1041 Trust return and issue the K-1.   Then you enter the K-1 into your personal return.  

the administrator of her estate is the one responsible for filing an estate trust return if one is needed. the Admin is also responsible for gathering the tax info needed to prepare the return. ask the accountant, he might have info as to where to get the tax documents.