Those do look to be quite good shape. Cleaning the 10/22 synthetic stock with liquid soap, water and a rag should be fine. It will get the previous owners gunk off it also. I say then to take an old toothbrush with some gun oil and go over all the metal parts to clean any grim and rust, clean the action, run the barrel and lubricate it. Good to go.
On the 870, you can certainly rub some oil into the stock and forearm or whatever product you decide to use. Then do the same with the exterior, metal parts and action with it. Maybe get them some stocking stuffer cleaning kits if they don't have what they need already, a sling for each, studs for the sling if they don't have them, some targets, ammo and safety gear. (shooting glasses and ear protection)