Given the state of the Hab's D so far, IMO the quickest and cheapest fix is for Bergevin to contact the management at Ak Bars Kazan to make a deal to bring Markov home...
Montreal still has the cap space to pay him and it wouldn't cripple them by having to part with high draft picks or a starting player to make a trade elsewhere
In return, Montreal sends Scherbak to Ak Bars on a sabbatical to get some pro experience in the KHL, and pays his salary along with a "development fee" to cover the costs of his playing on the team
Montreal fills the hole at D becomes an instant contender
Ak Bars gets the use of an exciting young prospect who won't see time in the NHL this season
cap space gets used fruitfully, no players/picks get wasted on a rental