The sentence that is punctuated correctly is:
"After driving all day and night, we finally reached our destination, and we happily went to sleep."
All other sentences have punctuation issues:
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"In 2019 eight new students enrolled in our school, but only five of them stayed." - A comma should be placed after "2019": "In 2019, eight new students enrolled in our school, but only five of them stayed."
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"For about 3 minutes, the helicopter hovered overhead, and then flew away, to the east." - The phrase "to the east" should not have a comma before it: "For about 3 minutes, the helicopter hovered overhead, and then flew away to the east."
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"On Monday I am going to go hiking but after that I will come by to visit you." - A comma is needed before "but": "On Monday, I am going to go hiking, but after that I will come by to visit you."
So, the first sentence is the only one punctuated correctly in the options given.