You said, " Also, I was hoping since it was a gift and the net proceeds & gain modest that perhaps it fell under some threshold that the gain would not be taxed? " Not at all. Your gift itself is not taxed but the gain that was accrued is taxed at the time of sale. In addition, you can't use amounts from 2016. Your basis is her basis from when she purchased it, not when you received it.
Example: your mother purchased the house in 19xx for $50,000. The value of the house at the time of the gift is $93,000. Your basis is your percentage of the $50,000, her basis, not her FMV.
