Can multiprocessing be carried out using 8031(or 8051)

The answer to this generic query is YES.

Now to proceed you need to define specifically what you want to do : Switching on Solenoid A - and 10 microseconds later switching on Lamp B - and 1 millisecond later switching on Motor C is also a kind of multitasking. The response times of all these gadgets are in 10s of milliseconds and hence to the user appear as happening simultaneously.

And incidentally where did the DMA controller creep in ?

Raghu