Design of Single input DC - Mutliple ouput DC circuit
Since the load current is quite low (opamps need less than 1mA), +15VDC from 48VDC can be obtained with a L78L15. But a series resistor before L78L15 is needed due to the maximum input voltage limitation of L78L15. Then -15VDC can be obtained from +15VDC with an ICL7660.

For 3-ohm load, it can be either a switching constant current driver or a 48V-to-3V Buck Converter. It needs to be a switching regulator, otherwise the wasted power will be too much.

For 9VDC to MCU circuit (I would expect it to be 5V or 3.3V, by the way), it can be obtained from +15VDC with a L7809. Note that the current consumption is not given, so I assumed it to be 20mA max. If higher current is needed then a switching regulator is essential for this section as well.