Select case string comparison
A classic solution to this problem is to use a data table - in your case probably in form of a dictionary. It depends of what type your values are - I assume they are some sort of view models? I'm also going to assume they have a common base class:

One time setup:

Dim dict As New Dictionary(Of String, ViewModelBase)
dict.Add("dashboard_home_vm", _Locator.DashboardHome_VM)
...


You can look them up simply by

Dim vm As ViewModelBase
If (dict.TryGetValue(Param.ToLower, vm)) Then
    return vm
End If
return Nothing


Adding a new view model would be achieved by simply adding a new entry to the dictionary.