Hunger, stress, uneasiness or asking for attention their might be several reasons for which cats start meowing and crying. But sometimes these reasons becomes serious and attention seeking.
Sometimes when you are busy in life routine, you forget to feed the cat, and they cry asking for food. You must try to keep the bowl or litter box fill every time but still if you forget, cat’s meow will call you seeking your attention that she is hungry and you forgot to fill the litter box.Source: catexpert.co.uk
Stressed and harassed cats seek attention and cry to release their strain. Cats meows become more powerful when they cry under stress and anxiety. Change in home settings, or when she sees new people in surroundings or seeing new animals which may hurt her can be the causes of her stress. Just familiarize the cat with new environment and people at home to release her strain until she becomes normal.