How do I file for my mom since she passed away last year

The filing of a deceased taxpayer's final return usually falls to the executor or administrator of the estate, but if neither is named,  then the task needs to be taken over by a survivor of the deceased, i.e. yourself.

The final return is filed on the same form that would have been used if the taxpayer were still alive, but "deceased" is written after the taxpayer's name. The deadline to file a final return is the tax filing deadline of the year following the taxpayer's death.

When filing the final tax return for your mother, TurboTax will ask whether the return is being filed for someone who has passed away in the Personal Info section. TurboTax will then report "Deceased" on the return.

For more information, please this TurboTax article.

I am sorry for your loss.