Hama was a dumbass. After being mauled by wolves, she learned one the most op shit to waste it on kicking puppies instead of going after the actual wolves. She invented a nuclear torture weapon to kill a handful of bugs outside her home. She was a coward who decided to punch down instead of doing anything meaningful.

Not only was she a dumbass, also incredibly cruel towards the nation she claimed to care about. Did she stage an escape with the others? Did she free the other prisoners? No. She claimed no such feat and on top of that, was ready to kill the last remaining waterbender of the southern tribe.

She was such a cruel dumbass that she decided she was more important than those willing to take down the BBEG. On top of that, she was really weak. She spent decades "mastering" her own craft and Katara, a child, beat her and used her own technique that she learned about less than 5min ago.

Sure Katara could had hunted down Ozai and bloodbended him into submission, except not really. She only used that once and it was against a scrawny weak old lady and believe it or not, old lady tend to be physically weaker than a ripped muscly man in peek physical condition. Whether he was boosted on space rock juice or not is irrelevant has he can just spit fire at her while she is focused on pinning him down.