Sometimes after the death or departure of a person or animal in your cat’s life, she will vocalize to express her grief. This can be a normal part of the grieving process. The best thing you can do for her is keep her schedule the same (or as close as possible) and spend some extra cuddle and playtime with her. With time, this problem should take care of itself.
If your cat is new to your home or has just gone through a change (move, new person/animal in the household, person moved out) and has just started her talkative behavior, be patient. This may be happening due to the transition and will stop on its own if the behavior is not encouraged. Remember, even scolding can be perceived by your cat as attention, and thus encourage the behavior.
Courtesy The Humane Society of the United States,