Thank you for your question.
Your mother is suffering from urge incontinence relayed to a condition called overactive bladder. She needs to see a gynaecologist who can take a detailed urinary history and rule out an acute urinary infection first. She may benefit from learning pelvic floor exercises and with vaginal estrogen therapy. If you can find a urogynaecologist that is best so she can be taught to retrain her bladder to hold for longer periods. There are also some medicines that can help stop hr leaking in bed at night. Often patients require additional tests like ultrasonography to confirm they are emptying the bladder completely and another test called urodynamics followed by a cystoscopy to look inside the bladder if her problem does not settle with conservative measures.