Steve Bruce had an uneasy close-season with strong rumours he was set to be replaced by Thierry Henry by Villa's new owners, who saved the club from financial ruin.
Villa's finances have improved since NSWE, a company jointly owned by billionaires Nassef Sawiris and Wes Edens, came forward last month with a "significant investment".
David Marshall's poor kick out from his own goal allowed El Mohamady to swap passes with Conor Hourihane and the Egypt worldwide picked out the bottom-left corner with a shot the goalkeeper should have saved.
But in the 14th minutes, the hosts' poor defending gave room for Tommy Elphick, making his first start for his team since January 1, to head in the equaliser unchallenged from a corner kick.
Bruce is confident of keeping Grealish beyond the end of the transfer window but expects to face a fight for his services.
Speaking to AVFC.co.uk about his return to Villa Park, the 20-year-old defender said, "It's great to be back".