Emery has told both players they are surplus to requirements and can leave before the European transfer window shuts on September 2.
"We have some players, they know their situation," said Emery.
"For example, Elneny and Mustafi know their position in the squad and really I want the players to be happy here, I want the players to be protagonists here.
"Last year with Mustafi and Mo, when they didn't play they weren't happy. I spoke with them a lot of times last year and this pre-season and I think it is positive for them to leave and sign for another team where they can be protagonists and be happy and continue their careers."