Which from following complexes is an example of $\text{MA}_4\text{BC}$ type distereoisomers ?

The general formula $\text{MA}_4\text{BC}$ represents an octahedral complex with one central metal atom $\text{M}$, four identical ligands $\text{A}$, and two different ligands $\text{B}$ and $\text{C}$.

Analyzing the given options:

$[\text{Pt}(\text{NH}_3)(\text{H}_2\text{O})\,\text{Cl}_2]$ is of the type $\text{MA}_2\text{BC}$ (where $\text{A} = \text{Cl}$, $\text{B} = \text{NH}_3$, $\text{C} = \text{H}_2\text{O}$).

$[\text{Pt}(\text{NH}_3)_4\,\text{ClBr}]^{2+}$ is of the type $\text{MA}_4\text{BC}$ (where $\text{A} = \text{NH}_3$, $\text{B} = \text{Cl}$, $\text{C} = \text{Br}$).

$\text{Pt}(\text{NH}_3)_2\,\text{Cl}_2$ is of the type $\text{MA}_2\text{B}_2$ (where $\text{A} = \text{NH}_3$, $\text{B} = \text{Cl}$).

$[\text{Co}(\text{NH}_3)_4\,\text{Cl}_2]^+$ is of the type $\text{MA}_4\text{B}_2$ (where $\text{A} = \text{NH}_3$, $\text{B} = \text{Cl}$).

Thus, $[\text{Pt}(\text{NH}_3)_4\,\text{ClBr}]^{2+}$ is the example of $\text{MA}_4\text{BC}$ type complex, which exhibits geometrical isomerism (cis and trans forms), and these geometrical isomers are diastereoisomers.