Protect And Herd

If you're wanting to do all of Hemet's quests, one after another, you can follow Hemet along, complete all 6, and turn them in as a complete group.

You do not need to turn one in at a time in order to get the next one he gives.

https://www.wowhead.com/npc=191205/hemet-nesingwary#comments Go read why Hemet said he's retiring. He's still hunting, not just "pick flowers and want peace and love". That's just nonsense head canon you made up yourself so you can be pissed about something.

Hemet Nesingwary offers six Quests, each to hunt an Elite enemy then report to his son, [npc=194590], at Camp Nowhere.

The six Quests are as follows, offered to the Player one at a time in this order:
Protect And Herd
A Shadow In The Ice
Pruning The Pack
The Face of Death
Old Stonetusk
Hunting the Huntmaster

/way The Azure Span:Dragon Isles 44.96 40.09 Protect and Herd
/way The Azure Span:Dragon Isles 46.67 38.67 A Shadow In The Ice
/way The Azure Span:Dragon Isles 65.46 25.86 Pruning the Pack
/way The Azure Span:Dragon Isles 63.51 15.62 The Face of Death
/way The Azure Span:Dragon Isles 45.02 40.91 Old Stonetusk
/way The Azure Span:Dragon Isles 63.83 59.04 Hunting the Huntmaster

Although you can pick up and turn in all six Quests at once, note that Hemet Nesingwary may not be present at these locations.
You have to wait for him to arrive in his Wagon before he will offer each Quest.