There is a difference between being a baalas chessed, and being a shmattah. The shmattah is only perceived as good as its last good job. You can do something 1,000 times for someone, but if the 1,001st time you say no, all the good you did is forgotten quickly.
There is such a thing as being good to a fault. If your friend is neglecting her family in order to do these things for other people, her priorities need to be reassessed. Quickly.