How do I report life estate sell of my mother's home? She is still alive and the proceeds were all listed on the 1099 as mine.

My mother changed her deed to a life estate with only me in 2013. This past year we had to sell the home and move her into a new home. The 1099 I received only shows me as receiving the proceeds from the sell. The proceeds were used to purchase her a new home and she lived exclusively in that home prior to sell. How do I report this on my return? There was also never a gift tax return filed at the time the deed was changed because we were not aware of any need.