Father passed away without nominee how to get control of his accounts

My family and I are American citizens. My mother and father were born in India. We live in America. My father passed away a few months ago. My father still has money in about 4 different banks in Gujarat, India (Kotak, Central Bank of India, Bank of India, Bank of Baroda). My father’s name is the only name listed on the accounts. I do not think he provided a nominee on the accounts. I have all of the banking documents—checkbooks, passbooks, etc. I have 2 main questions: 1. Can my mom gain control over my father's bank accounts without having to go to India? If yes, how can we gain control without going to India? 2. If we do have to travel to India, what is the process for gaining control over his accounts? How long do you think this process might take? Please let me know if you'd like any additional details. I very much appreciate it. Thank you so much.