There is 1 OH- in 1 molecule of NaOH.
Also, there is 1 H+ in 1 molecule of lactic acid.
So the reaction is simple.
so just equate the moles
moles of OH- in NaOH = moles of H+ in lactic acid
26.8 x 0.07 = 250 x Mole of lactic
Moles of lactic = 0.0075
so mass = 0.0075 x 90.8 = 0.681 g
Losing eltron is the answer