Mom periodically abuses drugs. Should I trust her to babysit ?

My mom smokes wet every week. About once a week. Claims she won't do it if my daughter is there , she goes off the wall for like a week out of the month doing pills , alcohol and whatever she can find. Then after a few days she is back to normal. My entire life she kind of been manipulating me , and I feel like she is doing it now with my daughter. Telling me she won't do drugs around baby , and I always believe her. Well now she is posting stuff and I know she is on something and she is supposed to babysit tomorrow. Am I a bad mom for letting her babysit , should I put her in daycare ? That's my only other option.... But who says at daycare she will be safe ... IDK what to do !