Maybe she doesn't.
If a person's mom truly wants a son to fail, then she needs help.
If she doesn't & the son believes she does it would be advisable for the son to seek help. Better yet, at least to start with, the son might brave an honest and kind approach to mom and just ask the question. The answer ( and even the question) might be surprising to both. At the worst if the answer is yes, the son will know.