Exclusive SUMs with CASE
Here's one way to make them mutually exclusive:

select count(case X when 'A' then 1 end)
     , count(case X when 'B' then 1 end)
     , ...
from (    
  select 
    case   --'Before Admission'
    when ((EvalCheckboxDate &lt; UnitArrivalTime) 
     and (m_value&lt;&gt;'No' or m_value   is not null)) then 'A'
           --'Within 24 Hours'
    when ((EvalCheckboxDate &gt;= UnitArrivalTime 
     and EvalCheckboxDate &lt;= dateadd(hh,24,UnitArrivalTime)) 
     and (m_value&lt;&gt;'No' or m_value is not null)) then 'B'  
    when ...
    [...]
    end as X
  from TFDataset
) as T


I.e. the idea is to use one case stmt to classify each row and then count the amount of each one. Thye code will be a bit simpler if you can live with something like:

select X, count(1)
from (    
  select 
    case   --'Before Admission'
    when ((EvalCheckboxDate &lt; UnitArrivalTime) 
     and (m_value&lt;&gt;'No' or m_value   is not null)) then 'A'
           --'Within 24 Hours'
    when ((EvalCheckboxDate &gt;= UnitArrivalTime 
     and EvalCheckboxDate &lt;= dateadd(hh,24,UnitArrivalTime)) 
     and (m_value&lt;&gt;'No' or m_value is not null)) then 'B'  
    when ...
    [...]
    end as X
  from TFDataset
) as T
group by X


and then transpose the result in the application