AHMED AND THE OLD LADY
by JON GODDEN 203 pages. Knopf. $7.95.
THE PEACOCK SPRING
by RUMER GODDEN 274 pages. Viking. $8.95.
In the pantheon of Hindu gods, Saraswati is the goddess of pen, ink and books. She must have given the young Godden sisters a double blessing. Half a century later, the ex-colonials are still writing with fecundity and styleoften about their childhood in India. Jon, 70, has just produced her tenth novel; Rumer, 69, her 15th. Rumer has also written poetry, stories and children's books. In addition, the Goddens have collaborated on two...