Minato could possibly blitz Hashirama...>_> just saying. 30 meters is kinda short. Bee cleared something like that in an instant when Juugo tried to smash him. Fast ninja can be blitzed: Bee was blitzed by Itachi.
If he blitzes Hashi, even if Hashi blocked his attack. There'll be a kunai near him and he'll be dead....
...But Hashi probably wins this. If the blitz doesn't work then Minato would exhaust himself trying to fight Mokuton in the first scenario. Though Bunta can probably jump over all the Mokuton at once and go for Hashi directly. Still, that'll just be prolonging the inevitable...if Shisuusenju comes out...well...Minato can teleport home to take a nap. If only the Fourth Hokage has shown some other barrier techniques
...
In the second scenario Minato wins for sure. With BM, he can definitely blitz Hashi and murder him. If not, he can take on Mokuton with ST barrier then murder Hashi.