To try and tone up my flabby lower tummy ( due to 2 c sections)

watching with intent, i could carry my lower tum round in a wheel barrow

It's difficult to say without seeing it, usually crunches, reverse crunches, and cycle crunches will tone the punch area however if there's fat over the area the crunches will do little, the best way is to loose weight in general because you can't spot reduce fat.