Solution

Staminode is an often rudimentary, sterile or abortive stamen, which means that it does not produce pollen. Staminodes are frequently inconspicuous and stamen like, usually occurring at the inner whorl of the flower, but are also sometimes long enough to protrude from the corolla. Caesalpinioideae flowers - Inflorescences racemes, spikes or cymes, flowers small to more often larger and showy, bracteoles small or absent. Flowers mostly slightly zygomorphic. Sepals usually free, commonly imbricate. Petals equal, free, upper one usually borne internally to the adjacent lateral petals. Stamens mostly 10 or fewer by reduction to staminodes, often of unequal size and long exserted, anthers usually opening by terminal pores or longitudinal slits.
So, staminodes are characteristics of Caesalpinioideae and not of Liliaceae and Papilionaceae.
Therefore, the correct answer is option C.