@qbteachmt An earlier post stated "She had the property for 30 years and added the kids on 20 year ago.."    So yes, up to the date of transfer she owned the property, but the date of transfer was long ago.  Nevertheless, she treated the property as her own, reporting all of the rent and expenses. 

I think we have all the information to resolve this -- the sale goes on Mom's return, and the kids can deal with the 1099-S as best they can.  The sins of the mother are being visited on them.  But if you hang around here long enough, you can always get the answer you want, even when it's wrong.