Cats are fighting now dont know wat 2 do:(?

i have 2 cats, 1 is a female dats like 4 years old, well she had kittens an we kept 1 female kitten an shes 3 now, an they always got along they got along perfect an evrythn, well oneday the mama cat got outside 4 like 2days an when she came bak inside it was like her daughter didn't recognize her an the daughter would hiss an snarl at her mom an run an attack her, well we decided 2 seperate them an its been about a month an we feel bad we have 2 keep them in alil room at diff times instead of letting them roam around the house...anyone suggest anything??? I don't want 2 have 2 get rid of one:(