Fragrance diffuser bulb

FIG. 1 is a perspective view of our new and ornamental design for a fragrance diffuser bulb;

FIG. 2 is a front elevation view thereof, wherein the rear elevation view is identical to the front elevation view;

FIG. 3 is a left side elevation view thereof, wherein the right side elevation view is identical to the left side elevation view;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof; and,

FIG. 6 is a right side view thereof, showing the fragrance diffuser bulb in use with an electrical fragrance diffuser.

The evenly dashed broken lines in FIGS. 1-6 illustrate portions of the fragrance diffuser bulb that form no part of the claimed design. The dash-dot-dash broken lines in FIG. 6 illustrate environmental subject matter of the fragrance diffuser bulb that forms no part of the claimed design.