Assuming that the resulting dilute salt solution have a density of 1gm/ml, total heat evolved is H= ms[T2-T1]
=50x4.18[30-18]Joules =2508 J = 2.508 KJ
Now this amount of heat has been generated in a reaction involving 25x2.0 = 50 meq of acid/base.
So 1000 meq = 1eq acid/base should involve 2.508 x 1000/50 KJ = 50.16 KJ. This is 'Delta' H per mole for this neutralisation reaction.