There is no one "good" DAU/MAU number, they vary a lot: is the app paid or free? Is it free with ads or free with IAPs (or maybe no monetization whatsoever)? Is it a game or something else? Some games/apps with low DAUs (in tens of thousands) make more money than much bigger competitors so you really need to focus on specifics of your app. Let me know if you can share more details of your app...