The woman screamed for help and some beach-goers came to her son's rescue.
The 26-year-old allegedly threatened the Filipina maid that he would physically assault her and kill her.
An Egyptian security guard, 38, said in the investigation that he saw the victim walking out of the bar in a drunken manner during closing at around 3.30am.
The award, launched by the UAE's government during the Second Government Summit in 2014, is the largest of its kind, with a total prize money of Dh4.67 million.
The Dubai Municipality's move to set up beach ramps for the disabled and senior citizens is in line with the "My community ... A city for everyone" initiative launched by Shaikh Hamdan.