The fact that it was "quit claimed" in 2010 means very little.  You need to find out more.

For example, did the father continue to use the home after that?  What about the client and sister, did they use the home?  What was the purpose of the "quit claim"?  Was it actually sold to the kids, or was the title just transferred?  Was the father still on the deed as well?

Was the house sold because the father died, or is he still living?

When you say it was a "loss", how did you arrive at that conclusion?  What did you use for the Basis?