We know that at one time (even before her marriage to her husband) Monica was a professional supermodel (as Melanie), we know that she has a husband who is not shown to us (and who may well be one of those behind this conspiracy against her). Yes, we still don't know how and by whom the money belonging to this family was earned...But we do have reliable information that Monica is a successful executive and runs her own busines (Fashion Magazine).
Taking into account her (super)modeling past, we can assume that her probably wealthy(?) husband could help her at the initial stage of "Fashion Magazine" creation and invest some of his money in the development of his wife's business. In favor of it being him is the fact that before Monica lost everything, her magazine had no investors (she didn't depend on anyone), so it was either her own money earned during her supermodel career or her husband's money. (I'm leaning towards the latter).
Eventually Monica became the successful head of her Fashion Magazine, her business was thriving and profitable, she herself, as a successful businesswoman , media personality and Influencer, was known throughout the country, and her mysterious husband, as we know, suddenly ran away/disappeared/and was accused of some financial crimes for which Monica, who had nothing to do with it, had to pay for.