Back during my active duty days putting a vehicle to sleep for months or longer was part of the job. What to do when I got back to the real world depended on how the vehicle was put to sleep. If I left the battery connected it would probably be dead. Even a dash clock or other stuff that you would think are small loads will drag a battery down given enough time. Engine oil would be fine but I normally did a change prior to nap time. If not it was first on the list. Prior fuel treatment to limit degrading of the gasoline was a good thing to do but normally what was in the tank was still good enough to get me to a station to get some fresh fuel in the system. Tire air would be expected to be a bit low also. Transmission, power steering, antifreeze and brakes fluid would all be OK and I just kept the maintenance cycle going. If the time based change hit before mileage then the fluid got changed.
Fuel injected engines were much easier to wake up than a carburetor. Usually need to crank the engine a bit to get the carburetor full of fuel before it would fire so a good battery was a must have.
For the house side sanitize the water system, check the batteries and change the oil in the generator. The generator might take a bit to start and don't try running it until you have fresh fuel in the main tank. Let it run for a while with the breaker off (no load) before loading up the electrical side of it. Use electrical space heater(s) to load test it. Space heaters are good steady loads with a constant level of power demand for a generator exercise. Plus they are inexpensive and forgiving if the power tastes funny to them.
