What role did Italy play in the final years of WWII?
In general, Italy did not play a very large role in the last two years or so of the war.
Italy was not hugely important as a member of the Axis for much of the war at all. In fact, their main impact on the war was negative from the Axis point of view. The Italians did things like invading North Africa that caused them to need to be bailed out by Germany, thus forcing Germany to spread its forces thinner than it wanted to.
In September of 1943, Italy formally surrendered to the Allies. After this happened, Italy was split as a country. In the south, the government that surrendered to the Allies held sway because the Allies held that part of Italy. The rest of Italy was occupied by the Germans, who set up their own puppet Italian government. This means that there were competing Italian governments until the Allies conquered northern Italy. There were also Italian units fighting on both sides of the war.
Thus, Italy ceased to exist as a united country after September of 1943 and it was therefore unable to play a major role in the rest of the war.