What's the best way to import DVD into iMovie 11? My got a new Mac for Christmas and I'm trying to help her import a bunch of DVDs with home movies transferred from VHS into iMovie 11. 

Google turns up several results but most are trying to sell you an app to rip encrypted DVDs. Other results suggest using Disk Utility to copy the DVD into a .dmg file which iMovie would recognize as a camera it could import from, but that doesn't seem to work with the current version.

I was able to use Handbrake to rip it to an MP4 and import that into iMovie but I'm curious if there's a more efficient way that avoids two transcodes and would be easier to explain to my mom.
Not really, you've utilised the quickest, easiest and cheapest route available with doing it with Handbrake. Don't bother trying to find another piece of software that will do the job better, Handbrake is really the best when it comes to ripping and encoding Apple friendly formats. Thanks, hope this helps.