Hi, I'd like to help you with your question.
It sounds like your cousin may be grieving. In grief, people can express themselves in different ways. Grief has five stages, which include:
Denial- happens when we first learn of a loss. The feelings are so overwhelming that we block them out to protect ourselves emotionally until we have time to adjust.
Anger (the stage your cousin is in)- occurs when we being to realize what has happened. The feelings are overwhelming and hard to cope with so we turn them around and try to find an outside source to blame. It can be the doctor who told us our loved one died or a relative or friend. We blame so we can deal with a loss that has no explanation. We try to find a source that can be faulted so we have something to focus on.
Bargaining- when we feel vulnerable from our loss, we try to find ways to gain control again. We do this by trying to bargain our way out of the loss. Making deals with God, saying you'll be good so the situation will change. These things are ways to try to make the loss seemingly in our control
Depression- any loss can cause depression. Sadness, crying, loss of appetite, and trouble sleeping are common. This is when we begin to accept the loss and the reality of it hits us. The danger is when we feel so bad we want to hurt ourselves. Then professional help is needed.
Acceptance- this is when we are able to accept the loss and we start to deal with it. It is not about being happy about the loss, but more an accepting and calmness about it.
Your cousin is in the anger phase. She is looking for ways to blame others and she is becoming destructive. Has anyone tried to confront her? Acknowledging her pain and recognizing that she needs to face it is something she needs to be told. Is she willing to get help? A good start would be for her to see her doctor. Medications can help her feel calmer and give her a chance to get help.
Does she attend church? Maybe her pastor could talk with her. And someone can also talk with her daughter. She needs to know that her mom is not doing well and that what she is doing is not right. The family can offer support to her by offering to take her for a few days at a time to give her a break. She may be grieving as well and not be sure how to handle this.
Counseling is the best idea for your cousin. She needs to talk out her anger and grief. If she is willing, have her see someone. Here is a link to find a therapist:
Support groups also help a lot. If she can talk with others who have got through the same experience, then she can start to heal.
Also, the family can resist her actions. Don't allow her to act out. When she does, leave the room. As long as she feels free to hit and lash out, then she will continue. Tell her that she is not allowed to hurt anyone else.
Understanding your cousin's grief would help. By understanding what she may be experiencing, the family can approach her in different ways to see what works. Here are some resources to get you started:
On Grief and Grieving: Finding the Meaning of Grief Through the Five Stages of Loss by Elisabeth Kubler-Ross and David Kessler
Getting to the Other Side of Grief: Overcoming the Loss of a Spouse by Susan J. Zonnebelt-Smeenge
Awakening from Grief: Finding the Way Back to Joy by John E. Welshons and Dr. Wayne Dyer
You can find these books on Amazon.com or your local library may have them for you.
Let me know if I can help any further,
Since she won't get help or listen to reason, the best option is to leave her alone. Make sure she knows that you care about her and that when she is ready, you will be there for her, but otherwise don't come near her unless you need to. Unless she is doing something like threatening to hurt herself or someone else, you can't control her. She is an adult and unfortunately, she has the right to act out until she does something either against the law or something she can be hospitalized for.
If she won't cooperate with counseling, you and your family can still go. Talking to a therapist can help you cope with what she is doing. You can learn ways to handle her behavior and how to best respond. It will also help you and your family with the stress.
Her daughter also needs help. If you can work it out, have her attend counseling too. Or at least join an on line support group and try some of the other resources I recommended. That way, she won't feel so alone and will have an outlet for her feelings.
Also, put limits on your cousin's behavior. Start responding by not responding. By that I mean you can leave when she acts out, limit how much contact you have with her and generally respond in a loving but limited way. Your mum needs protected so have someone there with her when your cousin is around. Act in such a way as to protect yourself and your family members. This may also help your cousin see her behavior in a different light if everyone is reacting to her behavior in this manner.