Sorry for your loss. If your mother passed away in 2017, and you are preparing a Final Return, you need to use the 2017 software.
If you are preparing a T3 Trust Return, Intuit offers T3 software that you can purchase - ProFile. You will, however, need to register as an E-filer with CRA if you wish to use the ProFile software, or choose to print and mail. More information can be found here: https://bit.ly/2u0giy8