I'm so sorry for your loss!

There are several ways you can sign your mother's final return.

If you have been appointed by the courts, you can file as Executor or Administrator.

If you have not been appointed, you can sign "On behalf of the decedent" or "Personal Representative".

Please look at the two links below.  The first is especially important if you are claiming a refund on your mother's return.  Please look at the paragraph "Filing the Final Return".

https://turbotax.intuit.com/tax-tools/tax-tips/Family/Death-in-the-Family/INF12090.html

https://www.irs.gov/taxtopics/tc356.html

I'm sorry, my mother is alive.  does the irs have a rule that her taxes must be filed by me or her court appointed conservator? The conservator did not file last year.

my mother is alive.  She has a conservator through the court who did not file for her the last two years.  Should she file?