• Can my in-laws have right to my late husband

My husband died on the 5th of dec '13 due to illness. He had a business of sanitation with partnership with his mother  but  later  he became the sole proprietor after a deed of dissolution  in 2010. He also has a trade license as a sole proprietor of  the business.but after  my husband's death my mother in law says that  neither I, nor my 4 month old son  has the right to his property now. She says she is the guardian now and she would make her eldest daughter's son the proprietor of my husbands business.she says she will only give some money every month  for me and my son.have  i not any right to my husband's property after his death? Can i not become the proprietor of his business?can my in-laws  claim in my husband's property?
My husband  also has a  daughter from his first marriage. He had given divorce to his first wife according to islamic law.can she or her daughter claim share in my husband,s property?