Note that, if they lay you off, you're entitled to unemployment, etc. It's probably better to refuse to resign and also refuse to move. That way, you get whatever severance benefits you are due.
If you are at the company, or just resigned because of this unreasonable policy change, I highly suggest you use your local bar association's referral service (or some other means) to schedule an inexpensive consult with a labor attorney.
[Assuming US laws] In most states you can terminate employment due to "Changing of Terms and Conditions" and still get Unemployment. Of Course check your local state laws, but their is a prevailing myth that if you voluntarily quit you always forfeit unemployment, that is not true, it is harder for sure, however in a situation like this chances are you would win unemployment hearing
This would be then termination with cause. Employment agreements generally state that employees can be required to work from any location as required by the employer. Refusal is then called breach of contract and hence termination without cause.
There are limits. If you sign up for a desk job in LA with no mention of travel and then get shuffled every day to Chicago, NYC, ... then it's unlikely the courts would agree that it was a termination with cause if the employee refused to cooperate. Here the courts might find that a month is insufficient notice, they might find that since the job started in the office there was always a reasonable expectation that the employees would have to return to the office, there might be jurisdictional questions, and who knows what else. Without a lot more details I'd hesitate to speculate as to the legal outcome in this case.
IANAL - but for example, in canada, forcing employees to move,or even significantly increase their commute, is considered the same as unilaterally changing the employees pay, and cant be done without the employees consent.
If you are at the company, or just resigned because of this unreasonable policy change, I highly suggest you use your local bar association's referral service (or some other means) to schedule an inexpensive consult with a labor attorney.