is she only once a day? quest

Once you start a Merana quest, you can't end it until you finish. You can't start a new one until the one in progress is completed. There's currently no way to quit.

i meant i finished it so i was asking when do i get another

You only have one pet, and she's already Hydrus. So you can't do another Merana quest until you get another pet.

ok ty