What to do if exposed to MRSA Staph infection?

My 19month granddaughter, who lives with us, was just diagnosed with MRSA. She had 2 large boils on her bottom that had to be drained. We have a large extended family, including elderly, living in our home. Should everyone be tested. My mom, has a permanent trache. Is she more at risk than others? I have cleaned thoroughly, but do not know how to proceed. If we are carriers, can we reinfect my granddaughter?