The ornamentation design for a fob, as shown and described.
FIG. 1 is a front plan elevation view of a fob according to my new design.
FIG. 2 is a top view thereof.
FIG. 3 is a bottom view thereof; and,
FIG. 4 is a right side elevation plan view thereof.
The rear elevation plan view is the same as the front elevation plan view; the left side plan elevation view is the same as the right side plan elevation view.