Can a mother of two under c - section, do sit up's as exercise? it's 1yr and 8 months after surgery.

Yes: In general, yes. However, if you're having any problems since the c-section, you should see your obstetrician.

Of course!: I would highly recommend core strengthening exercises such as pilates.

may resume exercise: Even resume normal exercise of this point granted that there are no significant abdominal wall issues. That is if there is a hernia or a bulge you may want to discuss possible treatment with your physician prior to resuming situps and normal exercise.