If the total of both protons and neutrons is four, then the Atomic Mass is four. If the nucleus holds four neutrons and protons each, then the Atomic Mass is eight.
The actual calculation of Atomic Mass is done relative to one twelfth of a
However, generally this corresponds to the total number of protons and neutrons in the nucleus of the atom, since protons and neutrons are almost of the same mass each, and the mass of one proton is considered a unit.
Since the data given above does not make it very clear as to whether four is the total of protons and neutrons, or the separate number of protons and neutrons, the Atomic Mass would be either four or eight.