Subjective.
The behaviors that resulted in her actions were set in motion for years. A lack of discipline and consistency of expectations regarding personal behavior , manners.
Her outburst of frustration and acting violently is just another bad example for the kids as the top role model to them.

As a parent and now a grand parent my observation is this women did not value respect.
Had she, her three offspring would never have caused this reaction in her.
We have all witnessed parents allowing the kids" to be the boss".
A big mistake parents make is to ask their young kids if they want to go to bed or do you want some vegetables. Offering choices is certainly ok if the answer and selection is acceptable. Not when it contradicts your intent. Expect respect and accept nothing less is essential, starting at an early age. Teach your children well.

Was her actions subjective or objective...