First, I would like to express my condolences on the passing of your mother.

Yes, you can prepare and file a tax return on behalf of your Mother for Tax Year 2017. First you have to create a separate TurboTax online account for your mother's tax return. This will ensure that no confusion exists in the system. 

When entering the My Info (for your mother) the last item is "I'm preparing this return for ______ who is deceased". After specifying that you are filing on behalf of your mother it will request the Date of Passing. This is the only step you must take to prepare the return on her behalf. (please see the attached screenshot)

Below is a TurboTax FAQ with a few additional steps that must be taken upon the death of a family member.

https://ttlc.intuit.com/replies/3300219