More information about which platform you are developing for, which tools you are already using, and the reason you are profiling your memory to begin with would be helpful. Without that information I can only suggest the following ...
1) Unity Memory Profiler
I would recommend starting with the memory profiling tools included with the Unity3D editor. You can find out more about these tools here: http://docs.unity3d.com/Manual/ProfilerMemory.html
It sounds like you are already doing this since you have narrowed it down the the "Mono" item from the profiler. This is good, you now know that it is one of your scripts that is consuming the memory.
Make sure you are using the Advanced View. The advanced view of the Unity Profiler will give you more information about which scripts are utilizing your memory.
2) Textures
When it comes to Unity and memory I always start with the textures. It seems like every time I do something with dynamic loading or modifying of textures I end up creating a memory leak. Take a look at your scripts, particularly any that load textures, and try temporarily disabling this logic. Does it help your memory issue?
3) Observe and Optimize
If you aren't able to locate any scripts that seem like they could be causing an issue, I would try observing your game and locating the point where you see your memory spike. Try to identify what logic is running at this point in time. Disable individual scripts and run your scene again. Did this reduce the memory usage? Repeat this process until you locate the script or scripts responsible for your spike. Once you find these scripts you can try re-factoring them until you get the results you are looking for.