The intermolecular bonding in the solid is van der Waals dispersion forces. That means that it will have a lower melting point than diamond or graphite where you have giant covalent bonding. In fact C60 sublimes at 800 K (527°C). Diamond and graphite sublime at around 4000 K.
As the coin is rubbed, the particles in the coin vibrate (presenting kinetic energy in the particles i.e. heat). The heat is transferred as thermal energy.