Textbox RadioButton Code

In order to set the same group to some RadioButtons, you can set the GroupName property of the RadioButtons to the same value. For enabling a TextBox according to the RadioButton's state, you can use the ElementName property of the Binding. For instance, see the following StackPanel:

<StackPanel>
    <StackPanel Orientation="Horizontal" Margin="2">
        <RadioButton Name="op1" Content="Option 1: " GroupName="A" />
        <TextBox Width="200" IsEnabled="{Binding IsChecked, ElementName=op1}" />
    </StackPanel>
    <StackPanel Orientation="Horizontal" Margin="2">
        <RadioButton Name="op2" Content="Option 2: " GroupName="A" />
        <TextBox Width="200" IsEnabled="{Binding IsChecked, ElementName=op2}" />
    </StackPanel>
    <StackPanel Orientation="Horizontal" Margin="2">
        <RadioButton Name="op3" Content="Option 3: " GroupName="A" />
        <TextBox Width="200" IsEnabled="{Binding IsChecked, ElementName=op3}" />
    </StackPanel>
    <StackPanel Orientation="Horizontal" Margin="2">
        <RadioButton Name="op4" Content="Option 4: " GroupName="A" />
        <TextBox Width="200" IsEnabled="{Binding IsChecked, ElementName=op4}" />
    </StackPanel>
    <StackPanel Orientation="Horizontal" Margin="2">
        <RadioButton Name="op5" Content="Option 5: " GroupName="A" />
        <TextBox Width="200" IsEnabled="{Binding IsChecked, ElementName=op5}" />
    </StackPanel>
</StackPanel>

Edited:

If you want the RadioButton to be checked when you click on the disabled TextBox, you can set the TextBox as a part of the Content of the RadioButton, like in the following StackPanel:

<StackPanel>
    <RadioButton Name="op1" GroupName="A" Margin="2">
        <RadioButton.Content>
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="Option 1: " />
                <TextBox Width="200" IsEnabled="{Binding IsChecked, ElementName=op1}" />
            </StackPanel>
        </RadioButton.Content>
    </RadioButton>
    <RadioButton Name="op2" GroupName="A" Margin="2">
        <RadioButton.Content>
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="Option 2: " />
                <TextBox Width="200" IsEnabled="{Binding IsChecked, ElementName=op2}" />
            </StackPanel>
        </RadioButton.Content>
    </RadioButton>
    <RadioButton Name="op3" GroupName="A" Margin="2">
        <RadioButton.Content>
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="Option 3: " />
                <TextBox Width="200" IsEnabled="{Binding IsChecked, ElementName=op3}" />
            </StackPanel>
        </RadioButton.Content>
    </RadioButton>
    <RadioButton Name="op4" GroupName="A" Margin="2">
        <RadioButton.Content>
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="Option 4: " />
                <TextBox Width="200" IsEnabled="{Binding IsChecked, ElementName=op4}" />
            </StackPanel>
        </RadioButton.Content>
    </RadioButton>
    <RadioButton Name="op5" GroupName="A" Margin="2">
        <RadioButton.Content>
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="Option 5: " />
                <TextBox Width="200" IsEnabled="{Binding IsChecked, ElementName=op5}" />
            </StackPanel>
        </RadioButton.Content>
    </RadioButton>
</StackPanel>