She needs to use the heat of fusion (ΔH(fusion)) and the equation q=mΔH(fusion) or q=nΔH(fusion) depending on whether or not ΔH(fusion) is given in J/g or J/mol. The reason why temperature is absent from the equation is that temperature does not change at a phase change, only the enthalpy does.
I hope his helps. Let me know in the comments if anything is unclear.