score:8
You didn't say what your starting point is, so let's do it from Naples, using Rome2Rio.com.
Herculaneum, Ercolano in Italian:
CTP bus leaves hourly, get off at San Giorgio a Cremano, takes 10 minutes.
Vesuvius (Vesuvio):
Vesuvio Express on demand, from Piazza San Pasquale, takes 40 minutes; connects you from Ercolano to the cone of Vesuvio.
You can hike the up the cone; it takes about 30 minutes to get up, the same to get down.
Pompeii (one 'i' in Italian: Pompei):
Trenitalia, 40 minutes, leaves every 30 minutes
Sita Sud bus, every 2 hours, takes 42 minutes
Sulga bus, once daily
Taxis are available in Herculaneum, particularly in the area of the train station, as well as from the Pompeii Scavi station.