If you grab the Wilcom True Sizer, then use the EMB file (Wilcom's native format). That should already have the correct colors (if not your mom should also have a stitch chart that shows the color/sequence) already assigned. The DST will not. The PES format is to my knowledge the only format that retains color functions. That's a double edged sword for the Brother multi-needle machines, even how it applies to DST files as well. If I recall though, your mom has the single needle sewing/embroidery machine (if I recall your previous thread correctly). If it's one of the more expensive sewing/embroidery machines, she should be able to handle DST files just fine. Just won't have the colors. If it's a mid range on down, chances are it has to have the PES format.
Bare in mind, while the EMB format is an embroidery vector format (if it's a true EMB file) and can be scaled a lot more then a raw stitch file (DST, PES etc), some areas might need to be redigitized to correctly do the new fills (run to satin to fill etc). So don't get overzealous with scaling it too much up or down. This is assuming that it's a true EMB file and not someone just importing a DST file and saving it as an EMB (akin to taking a jpg into a blank Ai file and saving it as an Ai file).
I do use the full version of Wilcom, so if you get stuck with the True Sizer program let me know and I'll try to help.