Decisions needed to be made quickly. Bruce decided not to try and move Helen; it was more dangerous and more difficult than the alternative, which was keeping the other two guys down. He chose to punch rather than kick; he could control where his fists went a little better than feet, and he had a better chance of a knockout without permanent damage.
Plus, with the two men now in a heap on the ground, it would be all too easy to grab Bruce's foot and unbalance him.
He stopped when he thought they were unlikely to get back up, either because they were unconscious or because playing possum was a better option than continuing to fight. Most people would have gone straight for Helen. Bruce went for the phone.
He planned to dial 911. He was no medic; the best thing he could do for the woman was to get emergency services on their way.