The given expression is as follows

 f = ab'(c + d'e) + a'bc')

 Finding complement using Demorgan's Theorem

 f' = [ab'(c + d'e) + a'bc']'

 f' = [ab'(c + d'e)]' [a'bc']'

 f' = [a' + b + (c +  d'e)'][a + b' + c]

 f' = [a' + b + c'(d'e)'][a + b' + c]

 f' = [a' + b + c'(d + e')][a + b' + c]