  We present an explicit formula for the transition matrix $\mathcal{C}$ from
the type $C_n$ degeneration of the Koornwinder polynomials
$P_{(1^r)}(x\,|\,a,-a,c,-c\,|\,q,t)$ with one column diagrams, to the type
$C_n$ monomial symmetric polynomials $m_{(1^{r})}(x)$. The entries of the
matrix $\mathcal{C}$ enjoy a set of three term recursion relations, which can
be regarded as a $(a,c,t)$-deformation of the one for the Catalan triangle or
ballot numbers. Some transition matrices are studied associated with the type
$(C_n,C_n)$ Macdonald polynomials $P^{(C_n,C_n)}_{(1^r)}(x\,|\,b;q,t)=
P_{(1^r)}\big(x\,|\,b^{1/2},-b^{1/2},q^{1/2}b^{1/2},-q^{1/2}b^{1/2}\,|\,q,t\big)$.
It is also shown that the $q$-ballot numbers appear as the Kostka polynomials,
namely in the transition matrix from the Schur polynomials
$P^{(C_n,C_n)}_{(1^r)}(x\,|\,q;q,q)$ to the Hall-Littlewood polynomials
$P^{(C_n,C_n)}_{(1^r)}(x\,|\,t;0,t)$.
