With Hronek now on IR, they're down to 6 "healthy" D: Biega, Bowey, Daley, Ericsson, Green and Nemeth.
In order to call up Lashoff under "emergency" it would mean the Red Wings deem (or at least told the league that) one of those guys is questionable for tonight's game.
Given that Daley, Ericsson, Green and Bowey have all been in and out of the line up with a myriad of injuries recently, it probably wasn't hard to get approved...
I'm guessing the recall gives the Wings a spare D while they're on the road tonight, as well as a guy that's close by in case Yzerman moves one of Daley or Green before tonight or Sunday's game. Or a guy they can dress if they want to hold Daley or Green out of the line up to preserve them for a trade.
He's likely back in GR before the deadline so he's eligible for the AHL playoffs. Not that it really matters for a guy like Lashoff, but if he's still on the NHL roster on Monday, he'll have to clear waivers again to go back to GR. I'm not sure if having to waive him on Monday affects their ability to get him back on GR's roster before 3PM that day.