assignment - How to store value in a For loop

I am using two For loops. When the inner loop finishes, I don't want to print but I want to store the result from the inner loop in some variable so that I can call that variable in the future. That result will come in the form of a list.

For example, in the 1st iteration,it is returning some value, e.g. {2,4}. in the 2nd iteration,it is returning {3,4}.

But I don't want to print them every time. I want some variable to store {{2,4},{3,4}}. How to do that?

Here I am retrieving all the data except Null.

tab={{{"option1", "option3", "option4", "optio", "Null", 

        "Null"}, {"option2", "option5", "option6", "option7", "Null", "Null"}, 
         {"option", "op", "Null", "Null", "Null", "Null"}}};

For[j = 1, j <= Length[tab[[1]]], j++,
  For[i = 1, i <= Length[Rest[tab[[1, j]]]], i++,

If[TrueQ[(Rest[tab[[1, j]]][[i]]) == "Null"], count++, count = 0]]
 Print[
Table[Rest[tab[[1, j]]][[i]], {i,1, (Length[Rest[tab[[1, j]]]] - count), 1}]] ]

Answer

In light of your update, is this all you're trying to do?

Cases[#, Except@"Null"] & /@ tab[[1, All, 2 ;;]]

{{"option3", "option4", "optio"}, {"option5", "option6", "option7"}, {"op"}}

Specific references to understand this code for your convenience:
Part, Function, Slot, Map, Cases, Except

---

If for some reason you feel you must use For loops, you can substitute Sow and Reap for Print as follows:

Reap[
  For[j = 1, j <= Length[tab[[1]]], j++,
   For[i = 1, i <= Length[Rest[tab[[1, j]]]], i++,
    If[TrueQ[(Rest[tab[[1, j]]][[i]]) == "Null"], count++, count = 0]
   ];
   Sow @ Table[
     Rest[tab[[1, j]]][[i]], {i, 
      1, (Length[Rest[tab[[1, j]]]] - count), 1}]
  ]
][[2, 1]]

{{"option3", "option4", "optio"}, {"option5", "option6", "option7"}, {"op"}}