Is the 1099-S in your name or your mother's name? If it is in her name, it sounds like she should report it on her tax return as a disposition of her rental property. The money she gave you would be a gift on which you would not be taxed. If the amount is above $15,000 she would have to fill out a gift tax Form 709. That is not an income tax form and is not filed electronically on TurboTax.
If your name was on the house and you received a portion of the proceeds directly, you would have to report it as a sale on your tax return. You would need to figure out with your mother what percentage of the sale you would report on your tax return, as well as the basis in the property. This would be reported in the Federal > Wages & Income > Investment Income > Stocks, Cryptocurrency, Mutual Funds, Bonds, Other (1099-B) section of your tax return.
@JKL0723
