How does Gerald help Eva and Daisy at Palace Bar?

That is correct....

Gerald: she looked young and fresh and charming and altogether out of place down here. And obviously she wasn't enjoying herself. Old joe meggarty, half-drunk and goggle-eyed, had wedged her into a corner with that obscene fat carcass of his--

Gerald: the girl saw me looking at her and then gave me a glance that was nothing less than a cry for help. So I went across and told Joe Meggarty some nonsense – that the manager had a message for him or something like that – got him out of the way – and then told the girl that if she didn't want any more of that sort of thing, she'd better let me take her out of there. She agreed at once.