Battery, Alternator or Voltage Regulator?

[JAB'70]

Here is the symptom(s). Drove my truck to work Friday, about 40 miles both ways. Came home parked it for about 2 hours. Drove it later that that night to met for wife for dinner (about 20 miles round trip). Left the eatery, then had to make a stop before heading home. When I came out of the store, would not start. It barely turned over, I inspected everything then came to the conclusion that the battery was dead. Called my son who came and gave me a jump. while heading home (about a 5 mile drive) The lights and instrument panel dimmed and the radio would not come on. Any comments???