"cita" at the end of a word its a diminutive (XYZcito or XYZcita). This could be use in people or objetcs.
Example: "Avioncito" mean little airplane (Avión : Airplane)
On the other hand, "mamacita" is not really a diminutive, but a expretion, similar to "babe". Is used on women ( most common to pretty young women). Example: "Tranquila mamacita" (Take it easy babe). Or "Hola mamacita" (Hello babe) , when trying to flirt.
This kind of expretion is also used on men, but with "papacito". EX: Two ladies (friends) see a good looking guy, then one tells the other "Hey, look that handsome guy" ("Oye, mira ese papacito")
I hope it was usefull for you.