If the property is on your mother’s name, then she need not take anyone’s permission or consent to dispose or alienate or transfer or sell the same to anyone of her choice as per he desire.A property in the name of a married woman shall be her own and exclusive property in which nobody has any claim or right.
The property is self acquired/gifted or the property comes from her parent’s side, then she is entitle to alienate the property. And she alone cannot alienate the property, which comes from her husband’s side without your consent.
Your mother can sell a property if she has purchased the same from and out of his own funds and you can not question the same. But if in case where the property came through succession after the death of anyone of your family members and where she got such right in it, she can not sell it without your consent. Even if she purchased a property of of the funds from others she can not sell without getting consent of other family members if any, including you.
Since your mother is the absolute owner of the property by virtue of registered Sale deed which was executed by her husband, she can transfer the property without obtaining consent of the children.
Reference: Hindu Succession laws, 1956