The first share in mothers parental property will be of her fathers side legal heirs I. E class 1 heirs. Later her husband side will have share I'm the same. 

Your father and his siblings are the legal heirs of the deceased grandmother. 

Upon intestate death of your father and your father's sister their respective share out of their deceased mother's property shall devolve equally on their own legal heirs. 

Thus similar to your position,  your cousin is also entitled to her legitimate share out of her deceased mother's share in the property as a right. 

You have no rights to refuse your cousin's rights in the property. 

1. As per section 15 of the Hindu Succession Act the property of a female Hindu is liable for equal division among her sons, daughters, husband and children of her predeceased sons and daughters. 

2. Therefore even if your Bua has died before the right of her children doesn't get extinguished. 

3. In such circumstances your cousin still has share in the property and her claim for share in the property cannot be disregarded. 

1. See the daughter of your father's sister in absence of will in this case has right over the share of her mother along with other legal heirs of her mother.

Your cousin sister ie your bua's daughter has a share in the ancestral property as per the Hindu succession act.

Yes,Definitely. Your cousin can claim her right out of the right of share of your bua as per Hindu Succession Act 1956 and recent ruling of Supreme Court of India on 11th August,2020.

Your cousin has equal share in property on her mother demise 

2) your aunt share would be inherited by her and her siblings 

1. Since property described is ancestral property, Cousin Sister is entitled to claim the share of property that was claimable by her mother (Bau) under the Hindu Succession Act, PROVIDED there is no WILL prepared for the property. There is no exception to this.

1. If the property is self acquired it cannot be ancestral at the same time.

2. The property owned by your grandmother has devolved through intestate succession on all her children equally.

3. On the demise of your bua her share in the property of your grandmother has further devolved on her husband and all children including her daughter equally. The share of daughters is at par with sons in the self acquired/separate property of parents.

4. Your cousin has an indefeasible share in the property.

As you have already mentioned that the property is self acquired property by your grandfather so eventually all the children have undivided share in the property irrespective of their death their legal heirs will have to undivided share in the property show so sister of your father as well and her legal hair in case it is a possible to get relinquishment deed signed by you sister in this regard to sell the property otherwise any sale in this regard will be liable to be challenged their rights in the property cannot be ignored and it will be established in the court

Yes your cousin can claim the property 

- After the death of your grandmother , the self acquired property would be devolved upon her legal heirs. i.e.your grandfather if alive , and children i.e. your father as well & other siblings including daughters.

- Further , as your father has already died without leaving any WILL etc, then this property can be claimed by all the legal heirs. 

- Yes, legally your cousin having her right to claim the share of her mother equally to your fathers . 

Yes, she have eqaul right. Her mother share inherited in her.

If your grand mother dies intestate i.e., without distributing the property by way of Will or any other mode, then her children are entitled to share equally, and that, since the father of your cousin died, his share will devolve on his wife and children as such, your cousin has right in the share of her father alongwith her mother and her siblings.

yes your cousin can claim her mother share. 

Yes your cousin can claim it.

Madam,

The said cousin may claim the share of her mother. 

Yes she can claim share of her mother from property of her maternal grandmother.