expartee

my mother was owner of total 20 marlas.i have purchased land from my mother.i have purchased 10 marlas from my mother.
A has filed suit on us to take possesion of land.he said that i have already purchased 15 marls from my mother.and he is owner of land.
actually few years back my mother had given power of autorney to B. and B sold 15 marlas to A without my mother concern .she had no knowlege about this transaction.actualy A and B has played fraud with my mother.
interesting thing was that their mutation was not sactioned due to error in sale deed.so my mother was abled to sell 10 marlas to me.
i and my mother come to know about this fraud now when we have got expartee in case filed by A. i and my mother got expartee in case because ward member has given false witness that we were at home and refuse to take summons.
now we have appealed in session court.
i can proove myself that i was on my duty while he delivered summons to me.
but how my mother can take defence in this case because she also have important role in this case.she is house wife,how she proove herself right ? can she take family defence how i can be helpful to my mother?