A mother has been arrested in Florida, three months after her two young daughters allegedly drowned in Texas with cocaine in their systems, according to authorities. The case dates back to Feb. 11, when deputies with the Harris County Sheriff’s Office responded to a home in Katy, Texas, for reports of two children drowning. The victims, ages 2 and 3, were later found to have cocaine in their systems. The circumstances surrounding the deaths have raised questions about how the children were exposed to the drug and what alleged role their mother, Laura Nicholson, 23, may have played, according to authorities. Before being arrested Monday in Fort Myers, Florida, Nicholson was charged May 8 with two counts of injury to a child in connection with the deaths.…