What an awful situation and, as you know, one that so many grans on here are suffering. Try to think on the positive side, WendyH, if you can. The fact that your daughter-in-law has addressed the parcels could just be that your son has reminded her that they need to be sent and asked her to get them to the Post Office.
It's horrible to think that the only contact you have is the return of the presents that you're sending with so much love, and that you're looking for these to come back so that you still have that tiny bit of contact. Is there any way of contacting any of his friends to see if they know how he's getting on? Or could you even phone his house, even risking an angry response?