I am sorry that one near to you is an invalid. Encourage her not to distrust God. He will give her patience to bear with her suffering. Only God knows what her limit is. Neither you nor she know the limits of her strength, or how long this trial will continue. Understandably, this can lead to discouragement.
"God is faithful and will not allow you to be tempted above what you are able to bear." He pledges His faithfulness and how wonderful is this faithfulness!
Remind your friend of this and tell her to leave everything in God's hands without looking at tomorrow. Often that which you imagine to be so terrible and unbearable is not so bad when it actually happens. Your imagination makes things harder on you than God ever could. You want to know the future and you also exaggerate your suffering. Sometimes you become overwhelmed by events that have not yet happened. All moments are in God's hands. Walk humbly with God.