I guess you want to shade the area between the lowest curve and the highest curve for all x.
T = readtable('Book1.xlsx')
% create a common x vector:
x_all = [T.x,T.x_1,T.x_2];
x_min = min(x_all,[],'all');
x_max = max(x_all,[],'all');
x = linspace(x_min,x_max,1000);
% interpolate y, y1, and y2, based on the common x
% (there are some NaNs and/or Infs in some of the ys, so the
% interpolation needs to be done just using the finite values):
idx = isfinite(T.x) & isfinite(T.y);
y = interp1(T.x(idx),T.y(idx),x);
idx = isfinite(T.x_1) & isfinite(T.y_1);
y_1 = interp1(T.x_1(idx),T.y_1(idx),x);
idx = isfinite(T.x_2) & isfinite(T.y_2);
y_2 = interp1(T.x_2(idx),T.y_2(idx),x);
% get the min and max y for each x:
y_min = min([y;y_1;y_2],[],1);
y_max = max([y;y_1;y_2],[],1);
% create a patch to fill the area:
patch(x([1:end end:-1:1]),[y_min, y_max(end:-1:1)],'b','FaceAlpha',0.25,'EdgeColor','none')
% plot the original data lines:
hold on
plot(T.x,T.y,'.-',T.x_1,T.y_1,'.-',T.x_2,T.y_2,'.-')
