Black and white cat everywhere..

After my cousin died in a car accident this year, I have noticed black and white cats.

It started at my grandparents house about 2 weeks later that the cat came and meowed until i came out. he is never there unless i visit then he appears again. He follows me around the house and into the house, and when I go back to my home he does not come back until I do.

At my home, a black and white cat, the same as the other one will sit outside my window meowing, if I go out he runs away, but soon he will be back meowing again. He has never been seen there before until 1 week ago?

I had a black cat whom is now staying with my father, he is still my baby. He is now 10years old.

Can someone tell me why these cats are showing up meowing at me?