Many elderly folks are on multiple medicines to control any health issues. If you end up taking care of an elderly parent, make certain you know their medical schedule. Don't ration medicine. Keep them on it, and pray that somehow you'll be able to acquire their prescriptions. Polyphamacy is complex. They take those medicines in a proper order: with food or not, timing based on best absorption, as needed, etc.
When elderly folks get out of their homes and into a new environment, confusion will often result. They are disoriented by the surroundings. This will right itself by YOU doing things to “center” them. Putting familiar items from their homes in their living space, talking about fond memories, keeping them on a schedule, etc will all help. The situation will no doubt make them feel helpless, and it's possible to see tempers flare, mental instability, and open anger.
Elderly folks are often a wealth of knowledge. They have sometimes lived through harsh times, and or have experiences with older knowledge that could be very useful about ways to cope in the future. You should tap that knowledge. Really listen to them.
It goes without saying that special events could occur. Things like incontinence from the disturbance in their normal cycle. Falling down when getting up in the middle of the night in a strange place. Some elderly are closet alcoholics. They may have been abusing quietly to cope, and now in a strange place and without their normal defense mechanism, may go into withdrawal. It frequently manifests in hospitals, but is not generally well known. Watch for it.
Women have had an enormous breakthrough in personal liberties compared to people in survival situations. That liberty may be quite curtailed by all sexes. A real adjustment in the ideas of freedom may occur, and the sudden mind-shift may result in all kinds of emotional manifestations. Be tender and understanding. Most women seek love and support and protection and then return affection.
Men think that they are in control and strong. Most are sadly NOT. The mind-shift will result in foolish and belligerent behaviour in order to assert dominance. It's wasted energy and rage turned inwards and outwards. Watch for it. Most men seek respect and affection and only then return love and support.
Most people react to new situations, and deal with the consequences later. That's not a pioneer way to deal with a SHTF situation. Be deliberate. If it's emergency, respond appropriately with enough force as necessary to adequately deal with it. Don't overreact scaring your family needlessly.
If dealing with a violent situation, don't waste a lot of time with words. Evil violent people know that normal reasonable people waste times with words and will take advantage. It goes without saying that this is the height of stupidity.
More than likely you'll be dealing, not with an evil person, just a desperate one.