
Given that \(ABCD\) is a cyclic quadrilateral.
As \(∠ADB = ∠ACB\) and \(∠DAC = ∠DBC\) (angles subtended by chords on the same arc), \(△AED \) is similar to \(△BEC\) by AA similarity.
Similarly, \(△AEB\) is similar to \(△DEC\) by AA similarity.
Given the ratios \(AB : CD = 2:1\) and \(BC: AD = 5:4\).
From the similarity of \(△AED \) and \(△BEC\), we have \( \frac {AE}{BE} = \frac {AD}{BC} = \frac 45 \).
From the similarity of \(△AEB\) and \(△DEC\), we have \( \frac {BE}{CE} = \frac {AB}{CD} = \frac 21 \).
Multiplying these two ratios gives \( \frac {AE}{CE} = \frac {AE}{BE} \times \frac {BE}{CE} = \frac 45 \times \frac 21 = \frac 85 \).
Therefore, the correct option is (C): \(8:5\).