My business is in tourism. I have a stable and rent horses to men and women. Sometimes the women wear very short clothes. Is my money halal? Is my work halal?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Renting horses and such for riding or sightseeing is lawful thing even if the renter is a disbeliever. But if this renting is accompanied by an evil act like exposing Awrah or committing bad acts then it becomes unlawful as it will then be helping in sin and Allah says: {……. Help you one another in AlBirr and AtTaqwa (virtue, righteousness and piety); but do not help one another in sin and transgression. And fear Allâh. Verily, Allâh is Severe in punishment.}[5:2]
Know also dear brother that avoiding haram earnings is a key to being blessed and getting satisfied with what one has.
Allah says: { …….And whosoever fears Allâh and keeps his duty to Him, He will make a way for him to get out (from every difficulty). And He will provide him from (sources) he never could imagine……} [65:2,3]
Allah says: {Say (O Muhammad SAW): "Not equal are AlKhabîth (all that is evil and bad as regards things, deeds, beliefs, persons, foods, etc.) and AtTaiyib (all that is good as regards things, deeds, beliefs, persons, foods, etc.), even though the abundance of Al-Khabîth (evil) may please you." So fear Allâh much (abstain from all kinds of sins and evil deeds which He has forbidden) and love Allâh much (perform all kinds of good deeds which He has ordained), O men of understanding in order that you may be successful.} [5:100]
Allah says: {And if the people of the towns had believed and had the Taqwâ (piety), certainly, We should have opened for them blessings from the heaven and the earth,.….} [7:96]
Allah knows best.