My husband and I will be out of the country and want his mother to have authority to make decisions on our behalf regarding our children.
If you are going to be out of the country for just a short time - vacation, for example, a letter granting her decision making authority while you are away should be sufficient. Also, a limited power of attorney including the dates you will be away should be sufficient. A letter should be addressed "to whom it may concern" and should include what decisions she is authorized to make during the actual time you are away. A limited power of attorney should be drafted by an attorney to make sure that the essential things are included. If you are going to be away for a long period of time, please consult an attorney to see what will be best under the circumstances.