Nomination Before Marriage

Respected sir/ madam, I am a widow women. My late husband worked in a reputed company of gurgaon, After my husband death, I applied for death claims, funds and insurance of my late husband in his company, but company told me that before marriage your husband mentioned the name of your mother in law in nominee for claims and funds, company told me that After marriage your husband did not changed the nominee from (mother to wife), And now just because of that reason my mother in law also demanding 50% share from death claims, funds and insurance. Sir, i just want to ask that nomination made before marriage is valid or invalid, because my husband made it before marriage, sir, someone told me that nomination made before marriage is invalid, because after marriage nominee will automatically becomes wife because she is the legal hier, so she is the only one to entitle all death , claims and funds of her husband, and mother inlaw has no right of demanding 50% share in death, claims and funds. Sir, i am in a extreme pain, please guide me, what is right and what is wrong because ((my mother in law is taking advantage just because her name mentioned in nominee, my mother in law was a government employer, and her husband was also a government employer but expired few years back, when her husband expired , she had taken all funds, claims and insurance of her late husband, now she is taking 2 government pensions, 1) her husband government pension , 2) her own government pension, and living happily in her husband house)) , Than also she is demanding 50% share in my husband company funds, claims and insurance , sir plz guide me , what should i do, where will i go, plz tell me that nomination made before marriage is valid or invalid, please guide me, i will be very thankful to you. Thank you Priyanka sharma Email id :- priyanka_sharma1988@yahoo.com