1) on her father demise your mother would have one fourth share in grandfather self acquired property , ancestral properties etc. you have not mentioned on what basis you say property is ancestral . property which has remained undivided for four generations would be ancestral properties

2) if your grand father had left will then your uncles will have to file for probate to prove will was executed by grand father and attested by 2 witnesses

3) i presume in partition suit you have sought injunction restraining uncle from selling the property

His self acquired property and his own share in the ancestral property (beyond which he could not make a bequest) shall devolve according to his will. In respect of those properties which are not covered by the will your mom succeeds equally along with other heirs.

If it is presumed that your grandfather's ot the wives are not alive now, then the entire properties shall devolve equally on all his four legal heirs.

Your mother being one of the legal heirs to your grandfather she will be entitled to 1/4th share in the properties.

She can file a partition suit seeking partition and separate possession of her 1/4th share the properties left behind by her father who died intestate.

Let her brothers come out with the concept of the so called will prepared in the year 1993, it becomes their responsibility to prove the genuineness of will by seeking probate of will through a court competent.

The court will decide accordingly after that.

In fact the court case by your mother will bring your uncles to a negotiation table and some compromise may be arrived at which if your mother agrees, shall be in her favor.