30^oE + 30^oW = 60^o, 1hour = 15^o, therefore 60^o gives 4 hours which means both are 4 hours interval. In time calculation, the west love an hour at every step which the est gains an hour. The wife is carrying the baby and calling the husband at 30^oE, 1 am, so the husband at the west will loose an hour at every step.
1 am before 12 midnight, westward minus 3 hours gives 9 pm in Sunday. Therefore, the wife calls on Monday while the husband receives the call on Sunday at 9 pm.