YES

2 decompositions
 #1 -----------
   2: f(h(a(),a())) -> f(b())

 #2 -----------
   3: c() -> b()

@Knuth and Bendix' criterion
--- R
   2: f(h(a(),a())) -> f(b())

--- S
   2: f(h(a(),a())) -> f(b())


@Knuth and Bendix' criterion
--- R
   3: c() -> b()

--- S
   3: c() -> b()


NOTE: input TRS is reduced

original is
   1: a() -> a()
   2: f(h(a(),a())) -> f(b())
   3: c() -> b()

reduced to
   2: f(h(a(),a())) -> f(b())
   3: c() -> b()