Yes
can electron and positron be combaied to give energy or is it just a theiory
Yes they can, and it is happening in your body all the time- The naturally occurring radioactive isotope of potassium (K40) can decay by the emission of a positron- in your body this positron almost immediately combines with an electron and they annihilate releasing two gamma rays.
Also, cosmic rays can create positrons inside you...
