This from the official site:
Following consultation with Thames Valley Police, both Hereford FC and Didcot Town submitted a request this morning to the Southern League that the match ordered to be replayed should take place behind closed doors.
Following the agreement of the League the match will take place on Tuesday, April 11th and no paying spectators will be allowed admission.
Details of coverage of the rearranged match will be confirmed in due course.
Update: Didcot have released a similar statement:
Didcot v Hereford - Game to be played behind closed doors.
Following The Southern League's decision to replay our abandoned game against Hereford FC, we can confirm the game will take place behind closed doors on Tuesday 11th April.The club's committee met last night to discuss the fixture and following discussions with Thames Valley Police, both clubs made the request to the league to play the game behind closed doors which has been agreed.