What happens in joint property of mother and son, if mother died?

If your mother died intestate then you , your brother and your father are the legal heir of your mother and her share will devolve equally among you  all i.e. 1/3 share each .

How is that the property has been jointly owned by you and mother? Is there any dispute among the legal heirs of the late mother's rights in the allegedly jointly held property?

You please answer the query raised by the expert Mr P.Venu Sir.  If you and your mother purchased it, then your mother's share will be divided among you, your father and your siblings in equal shares.

Upon death of your mother, in  the property jointly owned by you and your mother, your half share will remain in tact, besides that, you shall be entitled an equal share at par with the other legal heirs of your deceased mother, which will include your father also..

If nothing is mentioned in the ownership document about proportionate ownership, of shares 50% will be assumed to be the ownership of each of the joint owners. You, your brother and your father will be equal legal heirs to the 50% owned by your mother.