Walter interpreted "all the columns from b and d rows" as "FROM b TO d". I'm going to interpret it as "b AND d".
If the first variable in T has unique values, turn it into the row names, and just subscript:
T.Properties.RowNames = T.Var1;
T.Var1 = [];
t({'b' 'd'},:)
If they're not unique, use ismember to create a logical vector to use as a row subscript.