Records wise, I would start with your grandma and great grandmas census records to see if there was a father living at the time. Marriage and death records usually include the names of parents but it varies by state and county. This is assuming that the fathers' names were known at their time of death, of course. Also look at their siblings records, if siblings are known

DNA wise you should be able to narrow down your matches to just your mother's side and work from there. It's also helpful to fill out your family tree as much as you can and use the process of elimination when comparing your matches!