mother's property

No, son and daughter have no right over the money received by mother who sold her self acquIred property.

When you referred to the property as "her property", it is presumed that your Mother self acquired the property. In such a case, nobody has any demand for a share in the property or in the sale proceeds of such property. 

Is not the mother's husband, father to the son and the daughter? Anyhow under Mohammedan Law, property opens up for partition only after the lifetime of the deceased.

If I am not wrong, under the provisions of 'Woman's Property Act'  any property that comes into possession of a woman by any means is deemed as self acquired property?

The property belonged to mother and she is competent to dispose it.

No part of consideration can be shared by son and daughter, who were irresponsible in treatment of their father.