Succession Certificate

My mother died on May 2016, she was a principal in mcd school. My father also expired on Jan 1989 . I have one elder sister who is Govt teacher and i have one big brother who also died in 2012 n his wife and her son also leave the home after brother death. Now the question is my mother retirement funds PF and all benefits are stuck in mcd office as in gpf my mother mentioned me and my brother as nominee with 50 50 share n in year 2007 my mother published on newspaper for disowed my elder brother from moveable or in-moveable property but suddenly my sister in law has submit an application for her share in my mother retirement money and all benefits. N now she again not living with us, she is married now in her village. Now mcd said for making succession certificate. So my question is can i apply for succession certificate alone in the court or in the tahsildar in sdm court.. What will happen if i mentioned only me legal heirs as i already made an affidavit from tahsildar for me legal heir left... Please help me regarding this... How much time it will take to get succession certificate. Thanks Sanjay Kumar