File1 File2 File3 File4
10101  10101 10216 MB16
10304
10203

var=$(cat File1.csv)
var2=$(cat File2.csv)
var3=$(cat File2.csv)

if [var >= var2 && var <= var3]

awk '{print $1,$2=File4.csv}' File1.csv > output.csv

else

awk '{print $1,$2=File4.csv}' File1.csv > output.csv

Column1 Column2
10101  MB16
10302
10203  MB16
10116  MB16
10713
10511