Gentolman, I have a couple mountain bikes, one expensive and the other more moderately priced. The better one doesn’t get used during snow season so as to avoid road salt. I also have a moderately priced road bike that I haven’t used in years. If I were to buy a new bike I would buy one of those newer recreational bikes, the kinds that don’t shift gears or have fancy braking systems. Basically the kinds of bikes most kids used in the 50’s & 60’s before the 3 speeds came out (now 27 speeds…). My reasoning is that a simple old fashioned bike is easily maintained. Bend or break a derailleur and you’re walking home and the bike is going into the shop for an expensive repair. Have a problem with disc brakes and the bike is going into the shop. When I was a kid I could fix my own bike, No way could I do it now. Sort of like cars which in the modern world are very difficult for an average person to do much of any repairs on.
All that said, if all you want is an emergency tool so to speak to get home with, then yes a folding bike that you can keep in your vehicle would do the trick. It is actually a very good idea. Like with everything else you get what you pay for and $250 is not going to get you a quality bike. That doesn’t much matter though if it’s just an insurance policy to get you home someday. If you haven’t been biking, you really need to do some practice runs. It might not be pretty at first but better to get accustomed to riding now than do it for the first time in a real emergency. If early on you have to walk the bike up hills, so be it. You’ll get there. Weight is always an issue for bikes (and the less expensive bikes tend to be heavier) and carrying a backpack adds to your effort. My backpack has good shoulder pads and seems to distribute the weight well which in turn seems to make it less of a burden for me. Like WV, there isn’t much in the way of flat terrain up here either!
One of the most important things I learned over the years is unless the bike fits you well, it’ll take more effort on your part to ride it and/or it’ll be less comfortable. If it is possible to try on a bike before you buy it, do so. You can likely do that a bike shop so as to see firsthand what is comfortable to not before you go to Walmart. It’ll help you differentiate what you’re buying.