Hello. I would like to watch a drama with my mom, one I haven't seen yet. She's okay with all genres except ones that involve a lot of romance. She prefers action, so I'm thinking maybe a historical drama? 

Any recommendations would be nice :)

Six Flying Dragons (2016) - historical about politics from Goryeo to Joseon. 
Jewel in the Palace (2003) - Not action, but has a bit of the palace politics in the kitchen. 
Cruel/Heartless City (2013) - Action and crime with gangsters and police
Signal (2013)- Crime and murder cases. Butterfly Effect also thrown in the mix.

Time Between Dog and Wolf

Two Weeks

Warrior Baek Dong Soo

I would highly recommend Bad Guys (2014). A lot of good action throughout the series. If I recall correctly, there wasn't really any romance in it.

Tiger Cubs (2012) was also pretty decent. Action packed series about Hong Kong SDU (SWAT team). There was minimal romance in the series.

We're watching Signal now. Thank you everyone for the suggestions :)
Signal is a great choice! 
Otherwise there is Bitter blood. Maybe not the best ending, but it's really funny !
bloody Monday is like a typical serie with everything you want 
heartless city is a bit more mature and has that undercover+gritty feeling