Can an apartment complex do this?

My grand mother lives in Dallas, in some apartments. They are owned by a property management company called Skyline properties. Anyway, this morning she wakes up and finds a notice sent to all of the units stating that everyone including ADULTS had to be in their apartments by 11pm, or they would be fined, or EVICTED! No its not the city either we already called and asked, and they said they had no clue as to why they would impose a curfew for adults. Is there anything we could do? Does anyone know how to get a hold of the management/owner? BTW the apartments are called Carrier Arms Apartments, and they are in Grand Prairie Tx, any help would be appreciated!