Cosach contact with an offical

[toma]

4th and 20 from the 50, A33 advances to B40 on the run B head coach interferes (contact) with the official. Flag Unsportmanlike conduct 15yds from succeeding spot. (9-2-5-b)
WHO's Ball? Is it; A 1/10 from B25 or B 1/10 from B25?
Because A did not get the line to gain! Live ball treated as a dead ball. 

Enforced A 1/10 B25, Did we get it right?
 

[NVFOA_Ump]

Should be B 1/10 from B25.  This as noted is enforced as a DB foul and it's already B's ball since by rule the change of possession occurred when the 4th down play ended without A making the line to gain.