basicly, unless your mother has had her Own negative experiances (which I doubt), she is subscribing to the mass belief that all demons are evil and all angels are good.
Now, this is a sheeplike belief that is instigated my most of the current mainstream religions. It encourages the "believer" to accept a specific view instead of attempting to have their Own.
That being said: in a way it is bad. Most summonings are the equilivent of jumping a Demon in the middle of the night, chaining them up, and pulling them to your door. Where you can then bark orders.
Satanists usually have more "polite" ways of doing this, and usually only write down summonings for Demons that will teach and deal with intelligent individuals, versus being extremely vexed you dared to call them.
Angels and Demons are like humans in the way that they are not Inherently good/evil.
Light and Darkness are different, from the Thought of being good/evil.
Being made of a positive or negative energy does not necessarily mean you will act in a way that others will percieve as "evil" or "good". Essentially Angels and Demons are Both beyond such, and it is only the perspective of those outside that paints them either way.
I personally wouldnt share anymore of this with your family, if they are going to have such violently close minded reactions.
It is probable you didnt have your complete focus on the summoning, or didnt have your "reason" clear. If you are summoning you need complete focus, and you need to have the intent clear in your mind. If your calling a Demon, and also wondering what is going to be cooked for supper.. then the Demon is getting mixed signals and Will be wondering exactly what you think you're doing.
Respect, formality, intelligence, throughness and common sense are all needed if you wish to attempt Any summonings. Focus and mental dicipline also are key.
As long as you are not summoning for kicks, being respectful and of course being intelligent about the whole idea, there is nothing especially dangerous.