Unfortunately SCOM 2012R2 does not have a native report and/or view that allows you quickly view the maintenance history on a specific server or servers. This handy SQL query I have used many times over to get the history of a given server or servers to find out when the machine entered MM (Maintenance Mode). Using the query below, run against the OperationsManager (or Data Warehouse) DB, and specify the server(s) you are interested with the date range:
--- USE OperationsManagerDW SELECT ManagedEntity.DisplayName, MaintenanceModeHistory.* FROM ManagedEntity WITH (NOLOCK) INNER JOIN MaintenanceMode ON ManagedEntity.ManagedEntityRowId = MaintenanceMode.ManagedEntityRowId INNER JOIN MaintenanceModeHistory ON MaintenanceMode.MaintenanceModeRowId = MaintenanceModeHistory.MaintenanceModeRowId WHERE DisplayName Like 'server%.domain.net' AND ScheduledEndDateTime BETWEEN 'fromDateRange' AND 'toDateRange'