Can almond milk cause acne in someone who became a vegan 90 days ago and now only drinks almond milk instead of skim? She never had much acne before.

Possible. I have had patients who break out when they drink almond milk. It's rare, but it does happen. If the brand you are drinking is sweetened, or has additives, that increases the chances. Try an unsweetened one without any additives (or make it yourself). If you still break out, you may have to switch to soy milk; or the cause may be something else entirely, such as another component of your new diet.
Maybe. This is moot because all acne is manageable. If topical benzoyl peroxide has not cleared you in two weeks, get with your physician. I hope that becoming a vegan was an informed choice and that you realize that to preserve your health, you must supplement. The moral benefits are clear, but the actual health benefits have eluded mainstream science despite all that you've been told. Choose wisely.