Answer
1.97 kJ (lost by the system in fusion and gained on melting).
Work Step by Step
From the definition of heat of fusion:
$\Delta H=m.h_f=15.5\ g\times 9.95\ kJ/mol\div 78.11\ g/mol=1.97\ kJ$
This heat must be removed from the system for fusion to happen and added for melting to happen.
