Where did your friend get her medical degree? Many programs have biases against IMGs (not saying it's right, just acknowledging there is). As your friend may already know, looking at Match statistics, the typical preference is US MD > US DO > IMG. Your friend's board score is excellent for any peds program, but her IMG status may limit which academic programs she can get into. Competitive programs like CHOP, Hopkins, or Boston don't take IMGs usually. Even when they do, they're usually from Canada or western European counties, and not from Caribbean.
I would recommend her to research the programs by looking at the current residents - can she find a program that accepted IMGs in the last 3 years? To be blunt, less desirable locations would have better chances (Mississippi over Houston, St. Louis over Chicago, Arizona or New Mexico over California, etc.). Those would be good places to start with. Not that she can't shoot for the moon, but it'll be very unlikely.
Once she completes US peds residency, finding an allergy/immunology or pediatric rheumatology fellowship would get much easier. They are not very competitive fellowships and often don't fill all available spots.