with the rudimentary information you have given, it appears that the codicil supercedes the will with respect to the beneficiary, instead of your sister as originally envisaged, to her husband. It also appears that you have appeared in the probate case before the court and expressed your no-objection to grant of probate. thus the will and the codicil are presumed as proved and hence the probate is granted.
It also appears that your mother has been given life interest in the house. it is not clear whether to live in a portion of the house only, the rest of the portions enjoyed by the beneficiary of the will. Presuming that 'life interest' covers whole of the property, and includes living and/or renting out and enjoying the rent, the following opinion is provided:
Your mother alone can have the right of living in the house with or without the support of any other person of her choice. You can stay, if your mothers permits you. Except your mother, no other person, including the present title-holder (owner0 has got any right to evict you. Eviction at any time by your mother only can be enforced, during her lifetime. Later on you will not have any right to stay.