Has another one of your
friends been accused of beating up his wife or is it the same one?
Does the answer to this question have any effect on you whatsoever?
For the avoidance of doubt however - like any migrant granted ILR, a person granted ILR under the domestic violence rule will have recourse to public funds. Whether they will claim benefits for the rest of their life depends on their circumstances, their ability to work and to afford housing for example. A person granted ILR under the DV rule has no more entitlement to claim benefits per se than any other person in the UK who has recourse to public funds. S/he will not be able to claim benefits purely because s/he was granted ILR under this rule but whether her circumstances dictate that she is entitled to them.
I still don't understand why this matters to you though given that it is your friend's wife who is making the application!