If they just took it up, or if it's one of their kids - could be just a phase and it may pass in a relatively short amount of time when the novelty wears off. If they are practicing during daytime hours so they are not disturbing sleep or work functions (if you work from home), you may want to just endure it for now.
If they are playing at night keeping you up or during times that make work difficult, I'd suggest knocking on their door and explain how their practicing during certain times is causing problems for you and ask if they can practice at a different time. Most neighbors tend to be understanding and accommodating. Hopefully this will be the case and you can work out an arrangement that works for both of you.
If an arrangement is worked out and the drums still bother you, I'd look into the above suggestion about getting some ear plugs.
