As the property was inherited - you have a stepped up basis that is a fair market value of the property on the day your mother died.
If you had any improvement expenses - they should be added to the basis.
Your capital gain is calculated as (selling price) - ( basis) - (selling expenses)
I assume that you was a beneficiary of your mother's estate (even if it was not probated)
Capital gain should be reported by the beneficiary on the individual tax return - use schedule D part II long term capital gain - http://www.irs.gov/pub/irs-pdf/f1040sd.pdf
I suggest to report the sale transaction even there is no capital gain - to avoid any notes from the IRS.
Depending on your income - if you are in 15% tax bracket or below - there will be zero percent capital gain, otherwise it will be taxed up to 15%.
Let me know if you need any help to estimate your tax liability.