To plot a 3D-Surface/mesh you need a function that is dependent on two variables (https://de.mathworks.com/help/matlab/ref/meshgrid.html). Normally the result is then plotted on the z-axis. Your two functions seem to only have the time as an input. Plotting this as a surface would not work (or at least would not make sense).
If you have a function with two variables, check the link of the Matlab documentation I provided.
The following code shows how you could do something like you discribe, but without a mesh/surface. Note that the z-axis now shows values for y1 and y2.
x = linspace(0,10,10);
y1 = rand(1,10);
y2 = rand(1,10);
zerosVec = zeros(1,10);
figure(1); hold on; grid on;
plot3(x, zerosVec, y2)
plot3(zerosVec, x, y1)
xlabel('x')
ylabel('x')
zlabel('y1 or y2')
view([-25.10 33.53])
