Frankfurt Hostel or Hotel

I am travelling to Frankfurt for 3 days in late July with my 2 14 y.o. daughters and mother & am looking for suggestions on where to stay. Ideally we are looking for a hostel (so we can cook or get cheap meals). Are there any hostels that aren't in seedy areas? I'm not keen to take my daughters and mum to an area with addicts and sex shops. Please any advice you have would be great. thanks so much

There are only 2 hostels in Frankfurt. And to my knowledge none of them offers cooking facilities.
Frankfurt Hostel (however directly next to a sex shop and also the red light district is around the corner)
Youth Hostel Frankfurt

An alternative would be the Mainz youth hostel. Family friendly, only rooms with en-suite shower/WC. Next to a park in Mainz.
Frankfurt airport is between Mainz and Frankfurt. Public transport ticket from the airport cost the same in both cases (in your case the mini group day ticket for EUR 13,70 will be the best deal).
While Frankfurt is a pretty modern city with skyscrapers, Mainz is a more typical city for Germany.

THANK YOU - that is really great advice, and we will definitely be taking it up. Mainz looks lovely - and much more manageable for us.

Thank you