Mrs. Keating is your classic overbearing mother. She's overly involved in her son's life, and she uses an arsenal of weapons (interference, guilt-tripping, manipulation, bribery) to convince her son to do what she wants him to do. Keating has a really hard time ignoring his mother's "advice," especially early on in the novel.
"Fine," said Mrs. Keating, "go to the Beaux-Arts. It's a grand place. A whole ocean away from your home. Of course, if you go, Mr. Francon will take somebody else." (1.2.79)
The young Keating lets his mom convince him to go straight to work for Francon, and this choice sets Keating on the path to his eventual downfall. Mrs. Keating orchestrates her own downfall as well though. By pressuring Keating to marry Dominique instead of his true love Katie, Mrs. Keating ends up meeting her match and is effectively taken down by the icy and harsh Dominique.
In the end, Mrs. Keating seems as beaten down as her son, and the themes of the novel condemn Mrs. Keating for pressuring her son into living the life she wanted him to, rather than letting him be his own individual person.