The income that is obtained from an asset is issued under the name of the person who has paid for it. We can understand that your mother has not contributed any money to buy the house yet it is under joint ownership. So, she is not eligible for being the owner of the house despite being a joint owner. Hence, the money earned as rent under the house belongs solely to you and your mother has no portion in it. It cannot be shown as her income. If you entitle the income from the property under her name still it would be added to the owner of the asset. This rule is stated under the clubbing provision of Section 60.
If there is any contribution of your mother in the cost of the house then the rental income will be proportionally get distributed to both of you. The distribution of the rental amount will be made according to the ratio of the contribution made by you and your mother in the cost of the asset. The principal home loan can be considered as your contribution to the cost of the house.
As you are the only person who is paying the home loan, you are eligible to claim the tax benefits in respect of the EMIs that are paid by you.