Find unique names in a column based on a date range

In A4 copied down
=IFERROR(INDEX(Responces!$C$2:$C$20,MATCH(0,COUNTIFS(A$3:A3,Responces!$C$2:$C$20)+(Responces!$F$2:$F$20<$B$1)+(Responces!$F$2:$F$20>$D$1),0)),"")

This is an array formula & needs to be confirmed with Ctrl Shift Enter.
You can then use a sumifs formula for the other two columns.

in A4 use Fluff13 formula and in B4 use this formula:

=SUMPRODUCT((Responces!$F$2:$F$20>=$B$1)*(Responces!$F$2:$F$20<=$D$1)*(Responces!$C$2:$C$20=$A4)*(Responces!H$2:H$20))

Then drag the formula down and then to the right.

I'd stick with a sumifs
In B4 copied down & across
=SUMIFS(Responces!H:H,Responces!$C:$C,$A4,Responces!$F:$F,">="&$B$1,Responces!$F:$F,"<="&$D$1)