Federal Taxes: Do I Have to Pay Federal Taxes Off of Gross Sale of House Quit Claimed to Me

My mother quit claimed her home to me two years ago and mortgage stayed in her name. My mother paid for the mortgage monthly. I sold the home this year because she moved in with me. I received a 1099 for the gross amount of the sale of the home. Will I be able to only pay taxes on the net (after mortgage was paid off from the sale of the home)?

Thanks for any help!

Federal Taxes: Do I Have to Pay Federal Taxes Off of Gross Sale of House Quit Claimed to Me