Horns in a dream suggest superiority, either earned or conferred.
It is interesting that horns are supposed to bestow the powers of the animal on the wearer.
In pagan times, as well as some tribes today, the donning of horns signifies a particularly senior position within the tribe. Often the wearer is a shaman who, through dreams, can connect with other realms.
In chinese medicine, rhinoceros horn is reputed to be an aphrodisiac.
This is possibly because of its association with masculine power.
All of these significances, as we become more aware, can appear in dreams.