I think she's stronger than most of the commandments in terms of raw strength, she can't be actually compared to them because the commandments also have the power of the curses bestowed by the demon king. Mama hawk is actually a creature from the purgatory just like hawk, she's pretty damn strong.
This is not a huge spoiler but nonetheless it's still a mild spoiler.
I'm not gonna give too much of the movie away here for those of you interested in watching the movie. This is also the reason why they had to pull crap like Meliodas is out of commission due to the sword, etc. You would easily lose interest if you knew that they were a weak bunch that could be handled in less than 10 seconds. It was said most likely to keep the viewers interested in the movie. The six knights of black were nowhere near the power of the T.C, in fact the weakest T.C is probably more powerful than all of them combined.
