dsa
iPhone 6, iOS 9.2.1
Just because Snapchat shows data, when is the last time that you reset the data counter? You do not show that. Is it possible this used data before you turned the data off? Stocks looks like that amount of data would be a push notification. Do you have push notifications turned on for Stocks. That would use a small amount of cellular data to push since the Wi-Fi on the iPhone disconnects when the iPhone goes to sleep, unless the iPhone is connected to power.
I never had the data on to begin with. I suspected that it was using my data when switched off, so I reset the counter and opened snapchat, and it had used data.
If you have any notifications set up for Snapchat, such as push, it would use a small amount of cellular data whether turned on or not. You can check the other settings for Snapchat, and also contact Snapchat support with any other questions about it using cellular data.
dsa