已知正项等比数列\(\{a_{n}\}(n∈N*)\)满足\(a_{2018}=a_{2017}+2a_{2016}\)，若存在两项\(a_{m}\)，\(a_{n}\)使得\( \sqrt {a_{m}a_{n}}=4a_{1}\)，则\( \dfrac {1}{m}+ \dfrac {5}{n}\)的最小值为\((\) \()\)
A. \(2\)
B. \(1+ \dfrac { \sqrt {5}}{3}\) C. \( \dfrac {7}{4}\) D. \( \dfrac {11}{4}\)
