Judging from this score alone, it should not be considered "bad". It's not necessarily good, but at least it's "good"

Your mother has high expectations of you, and it is understandable that she wants you to get better grades. But her method is wrong!

Too much criticism and unrealistic evaluation will not only help to promote your study, but will dampen your enthusiasm for learning;

We should encourage you appropriately, analyze the reasons for the mistakes in the exam with you realistically, and find ways to solve the problems and improve your grades.

Grades and scores are relative. What is true is your knowledge and ability to improve. In fact, you should not care too much about your mother's opinion and evaluation. Know yourself well, straighten your position, define your goals, find your gaps and shortcomings, and really move forward towards your goals in a down-to-earth manner.

After all, your mother will talk about you, because she loves you and hopes you. You can also try to strengthen communication with your mother and strengthen mutual understanding between you two.