Forget tranquilizer darts - that's the stuff of Hollywood. Real police officers use taser, even on a wayward emu:
Authorities in Mississippi said they had to handcuff an emu and shock it with a Taser to remove the ostrich-like flightless bird from a roadway.
Oh, and they used handcuffs, too. I'm assuming they meant emu legcuffs: Link (Sadly, no photo of the cuffed emu)
If that seems overly crpytic...
I don't think my grandfather ever had to deal with emus. The occasional stray horse or such, plus the usual dogs and cats, but I don't recall him mentioning any emus.