Is an insurance company for an at-fault driver required to provide a vehicle to the victim that can perform the same functions as the victim's vehicle such as 4x4 and towing ability?

You don't mention which state you live in, but for most states, the answer is "no." Most states require that the at-fault carrier provide a claimant with basic transportation. On that same note, almost all states do not require the at-fault carrier to pay for the rental insurance (if you have full coverage on your own vehicle, it should transfer to a rental anyway).

This is a strange rule, actually, but in many ways it makes sense. The minute you get behind the wheel of you car, you're accepting a certain amount of risk. Along with that risk comes a duty to mitigate -- or lessen -- your damages, even when you're not at-fault for an accident (i.e., it ain't like winning the lottery if someone rear-ends you). "Basic transportation" is definitely a way to keep costs down.

But...talk nicely to your claims adjuster and they just might bump you up to a 4X4. And, again, your state might actually require a similar vehicle be made available to you.