Please let us extend our sincere condolences on the loss of your mother.
With respect to your tax question, your accountant is correct in their answer. Excess deductions on termination of an Estate (or Trust) are reported on Form 1040, Schedule A, Line 23. Also, any short-term (and also long-term) capital losses from the Estate (or Trust) should flow onto your Schedule D, and allow you to benefit from them.
However, you won't see places, or questions, in the direct TurboTax program interview, dedicated to these topics . . . because that's not they're supposed to be entered. Instead, if your mother's accountant (or some other competent tax preparer) did their work correctly, you should have received a document known as a Schedule K-1, which is a byproduct of a properly-prepared Form 1041 tax return for the Estate of a deceased taxpayer.
Assuming that was done correctly, then any allowable excess (itemized) deductions would appear in Box 11a of that Schedule K-1. Short-term capital losses allocated to you would appear in Box 11b of that Schedule K-1. Long-term capital losses allocated to you would appear in Box 11c of that Scheudle K-1.
Do you see where this line of reasoning in going? You really should have been given a Schedule K-1 document, from whomever handled the tax return(s) for your mother's estate. If you don't have one, then we would respectfully suggest asking your mother's accountant (who gave you the correct tax advice in the first instance, and would therefore seem to be a knowledgeable person) for help and assistance in creating one.
With a proper Schedule K-1 in hand, you can enter the tax data from your mother's Estate into your TurboTax program. When you make an entry for Schedule K-1, Box 11a, the amount will then automatically flow onto your personal Schedule A. Similarly, entries for Boxes 11b and 11c will flow onto Schedule D.
For mechanical instructions on where to begin entering the Schedule K-1 itself in TurboTax, you may refer to the following FAQ webpage, where those are detailed:
https://ttlc.intuit.com/questions/1900938-where-do-i-enter-a-k-1-that-i-received
You may additionally need to upgrade your TurboTax software to at least the Premier version of the program (although the software itself will let you know).
Thank you for asking this important question, and once again we are very sorry to hear about your mother's passing.
