You can have a virtual currency in your community and use it as a reward to the best answer to a questions, best members of the month, etc. You can install Virtual Currency from Tribe App store: How to install an app to my tribe community?7
Once the app is installed in your community, you can see the Virtual Currency on your admin panel:
Click on the Virtual Currency on the left tool bar to define a name and real value for your currency:
Choose a name for your currency (like Coin or point or ...). Choose the real money type (like CAD or USD or...) that you will convert your virtual currency to when a winner wants to redeem his/her points. Choose the conversion rate (the real value of each virtual currency compared to the real currency like CAD).
Please do not forget to Enable and Update the changes.