My mother in law is a smoker and drinker. The past week she's been bleeding from her ears. Could it be from her bad habits, maybe cancer?

Get her checked. An ear examination by a physician/ent doctor is advisable for bleeding from the years. It is unlikely that her smoking or drinking is the cause of this bleeding but certainly her health can be impaired due to her life style issues but only a medical examination and further testing can find the exact cause of her current medical problems.