You'll find more details on what occurred on the device leading up to this detection from the Windows Event viewer. I suggest looking for Event ID 911, which will help us better understand why this detection occurred.
In most cases, there is a script or application that launches explorer.exe to perform some further operations.
As this detection states "Generic.Ransom.C" there is also a possibility that this could have been a false positive. I suggest determining if any specific actions were taken on the device when the detection occurred. This could be something like opening a specific program or using a plugin to perform certain actions when saving files.