Do I file my Mom's gift tax and do I file as her?

In September 2014 my mom gifted me her house (valued at about $150,000). She passed away in March 2016. I sold it for about $90,000 in July 2017. She was very ill so I don't think she filed a gift tax. Do I have to file one in her name and with her social security number? She willed me everything else she owned and I have received that judgement in the the mail. BTW, I never lived in it, she built it for herself to retire in, and lived in it until the end even though it was gifted to me.