Six months sounds more like a Class A or B Misdemeanor. Typically these don't come with the no possession of firearms stipulation. Might want to check her sentencing requirements. If she is on probation in addition to the jail time, she can talk to her PO and they can advise you better. At the least, you could invest in a safe or lock box to keep it in.
As far as actually purchasing the firearm, you should have no issue in regards to her conviction and sentencing.
Aut viam inveniam aut faciam
U.S. Army Military Police (ABN) 1998-2003