hameN unko airport le ke/kar jaanaa hai.
Grammatically --- I think the infinitive verb phrase
unko airport leke jaanaa is formally the "subject" of the sentence. The VP has no (unmarked) direct object, so it's masculine singular -- thus the singular
hai rather than plural
haiN (and in the past tense, it'd be a
thaa).
Regarding lenaa ---
take a thing from someone = kisii se kuchh lenaa
take something(/someone) somewhere = kuchh(/kisii ko) kahiiN le [ke/kar] jaanaa
go somewhere to pick something(/someone) up = kahiiN kuchh(/kisii ko) lene jaanaa
Also, I feel like there's a slight difference in meaning between
le jaanaa and
leke/lekar jaanaa, but I'm having trouble pinpointing it precisely... But maybe that's a topic for another thread
