Is there a way to find the list of all metadata elements created and modified on the basis of date or user in a org?
You can query SetupAuditTrail to find specific changes, such as...
Find Changes By User
SELECT ... FROM SetupAuditTrail WHERE CreatedBy.Name = 'Brian Fear'
Find Changes By Time
SELECT ... FROM SetupAuditTrail WHERE CreatedDate = LAST_N_DAYS:10
Find Changes By User And Time
SELECT ... FROM SetupAuditTrail WHERE CreatedDate = LAST_N_DAYS:10 AND CreatedBy.Name = 'Brian Fear'
Note that aggregate results are not allowed, so you can't quickly find answers to things like "How many objects where modified by user X per month?" or things like that. If you need aggregate data, you would want to export the records and manipulate them in your favorite database or spreadsheet application.