The general rule of thumb is that anything attached to the house stays with the house. So if the cabinets in the basement are built in, they'd stay. Same with the display piece in the laundry room. If they aren't built in, then one option is asking the buyer if they would like those pieces to stay. If the buyer wants them, all is good. If the buyer doesn't want them, your family needs to remove them before closing. Have your parents' agent deal with asking the buyer.
The washer and dryer and freezer--this sort of thing is regional in the US. In some places, it's expected that you'll take most appliances with you; in others, that the appliances will remain with the house. The agent who is handling the sale should be able to steer your family on this. Appliances are frequently mentioned specifically in the sale contract, so there should be no surprises on this. Again, the buyers could be asked if they want the W/D. If they are first time house buyers, they might want the W/D to start with, until they can buy new ones on their own. But they might have a W/D that they already like and want to move into the house and being faced with having to remove the old units is time consuming and in many places, expensive.
The mason jars should be removed. If the bulbs fit light fixtures in the house, they can stay.
Even though your parents have no contact with the buyer, their real estate agent can contact the buyer's agent. This is one of the reasons you have an agent--to deal with details like this. If the house is already under contract, these details may have already been decided. Someone needs to check with the agent.
Things that I've appreciated being left behind when I move into a new place include manuals for the appliances that stay (stove, fridge), a list of the paint colors used in each room or even the paint cans if there's still paint in them, light bulbs (especially if a fixture takes an odd size or shape bulb), a roll of TP in one of the bathrooms, and take out menus for local places.
Once I moved into an apartment and discovered that the previous tenants had left behind what might have been a year's worth of recycling on the back porch. On the third floor. Lugging 10 huge boxes of cardboard and glass and plastic down to street level did not make me think very kind thoughts about them. Nothing should be left behind that would create more work for the people moving in.
