Usually the mother will return. But it may help to call some kind of wildlife program. I'm not sure what the equivalency would be In Canada, but here we would just make a call to the state wildlife agency, and they will direct the matter.
Now if It where me, and mind you this becomes a full time job, Try a salt lick out near the fawn, to try and coax the mother back. If worse comes to worse, They can be hand fed, and nurtured. Just break out the baby bottles, and do a search for proper milk and feed for an infant.
As far as Coyotes, kill every one of em you see. They are as bad as boars when it comes to a farmer/Ranchers business and livestock. They can destroy more land faster, than a republican Bulldozer in South America.
Stephen