I haven't located Annie's maiden name but there is a record of Edward Charters Overs on the Australian World War 2 nominal roll www.ww2roll.gov.au
That will give you his date of birth; service number; rank; enlistment and discharge dates and next of kin which is Annie. Unfortunately it doesnt state what her maiden name is. His army service records are in the Australian National Archives www.naa.gov.au
If you do a record search on that website using the surname Overs and his service number, you will get the catalogue reference for his service records. That reference has a link to request a copy of those records which may contain Annie's maiden name.